Higher Physics Whole Course COPY Flashcards
1
Q
Name the four Bosons.
A
- Photons
- W and Z Bosons
- Gluons
- Gravitons
2
Q
How are absorption lines in the Sun produced?
A
Photons of certain frequencies are absorbed by the gases in the outer atmosphere of the Sun.
3
Q
What is meant by fission?
A
Fission is when a nucleus of a large mass number splits into two or more nuclei of smaller mass numbers.
4
Q
What is the critical angle?
A
The angle of incidence (within a material) that gives an angle of refraction of ninety degrees.
5
Q
What quantity is always conserved in a collision?
A
Momentum
6
Q
What is Newtons First Law?
A
If balanced forces act on an object it will : Remain at rest or continue to travel at a constant velocity in a straight line
7
Q
What is the terminal potential difference, Vtpd?
A
It is the potential difference which is able to supply the user when the circuit is complete and current flows.
8
Q
What is meant by 1 Farad?
A
1 Coulomb of charge stored per volt
9
Q
What is 1 volt?
A
1 Joule of energy transferred per Coulomb of charge
10
Q
When calculating power should you use Vpeak or Vrms?
A
Vrms
11
Q
What is a coherent source?
A
Waves that have a constant phase difference (and the same frequency, wavelength and velocity)
12
Q
How can an elastic collision be identified?
A
Calculate the total kinetic energy before the collision and the total energy after the collision.
If the total kinetic energy before the collision is equal to the total kinetic energy after the collision then it is an elastic collision.
13
Q
What is the definition for 1 Newton?
A
One newton is defined as the force required to make a 1kg object accelerate at 1ms-2.
14
Q
What would happen to your apparent weight if you were standing on a set of Newton scales and were in a lift that was de-accelerating downwards?
A
Your apparent weight would increase, It would be equal to your weight plus the force to cause the de-acceleration downwards.
15
Q
In which mode is this operating?
A
Photoconductive
16
Q
What is meant by fusion?
A
Fusion is when two small mass number nuclei combine to form a nucleus of a larger mass number.
17
Q
Are all photons produced by energy level transitions visible?
A
No, some frequencies of photons may be in in the ultraviolet or X-ray frequency
18
Q
What force is carried by a Graviton?
A
Gravity force
19
Q
What force is carried by a Gluon?
A
Strong force
20
Q
What is the definition for current?
A
Current is the number of Coulombs of charge passing a point in one second.
21
Q
What is calculated from the area under a velocity - time graph?
A
Displacement
22
Q
Give an example of a Baryon.
A
Proton
Neutron
23
Q
What is potential difference?
A
The number of Joules of energy transferred per Coulomb of charge.
24
Q
From the graph, how can you calculate the internal resistance of the cell?
A
internal resistance = - gradient
25
What is a point source?
This is a source where the light spreads evely in all directions
26
What is the difference between distance and displacement?
Distance is the length of the actual path travelled, Displacement is the straight line distance between where you started and where you finished, with a direction.
27
If an incident photon is greater than the work function what happens to the rest of the photon's energy?
The electron that is ejected has the rest of the energy as kinetic energy.
28
What are the lost volts, Vlost?
This is the potential difference unavailable to the user because of the internal resistance of the supply.
29
Explain how an object reaches it's terminal velocity.
The weight of the object acts down towards the surface of the planet. As the object falls it accelerates, as it does this the air resistance up the way will increase as it falls faster. Eventually the weight = air resistance. This gives equal and opposite forces so the forces are balanced. This gives a constant velocity, terminal velocity.
30
In the following circuit what quantity will the voltmeter measure and why?
The EMF as NO current is flowing as the circuit is incomplete.
31
What happens to the source frequency during the Doppler Effect?
Nothing - it remains constant
32
What is the wavelength of a wave?
Wavelength is the distance from a point on one wave to the same point on the next wave.
33
When will total internal reflection occur?
* Incident light must arrive at the boundary at an angle greater than the critical angle
* Occurs when light tries to pass from an optically dense material to a less dense material (e.g. from glass to air)
34
What are the advantages of using a grating to produce an interference pattern instead of a double slit?
* Fringes are brighter
* Fringes are sharper
35
What is the Work Function?
The minimum energy required to eject an electron from a metal surface.
36
Explain why an LED may not produce light EVEN when it is forward biased and connected to a supply voltage.
* The electrons in the n-type conduction band are not provided with enough energy to move into the conduction band of the p-type.
37
In the Gravitational Force equation what is the distance, r?
The distance, r, between the two objects is the distance between their centres of mass.
38
How can you increase the spacing between the maxima in am interference pattern created using a laser and a grating?
* Decrease the separation of the sources (more lines per mm)
* Increase the wavelength of the waves (Use a laser with a longer wavelength)
* Increase the distance between the sources and screen/detector
39
Explain why a reverse biased p-n junction will not conduct.
* Energy is supplied to the p-type material by the battery.
* This increases the internal electric field strength.
* The electrons in the conduction band of the n-type do not have enough energy to overcome the larger potential difference of the electric field.
* Electrons cannot pass into the conduction band of the p-type so the p-n junction will not conduct.
40
If an unstable nucleus undergoes beta decay what is given out and what is the effect on the mass number and the atomic number?
An electron from the nucleus is given out along with an antineutrino.
The mass number of the product remains the same and the atomic number increases by one.
41
What is your weight in freefall?
0 Newtons
42
When will time dilation become apparent?
The stationary observer and a person or object moving at relativistic speeds experience time passing in the same way. Only when they compare the times they have experienced do they notice a difference. The person who is stationary will have experienced a longer time in comparison.
43
What is the evidence for dark matter?
The mass of a galaxy can be estimated by the orbital speed of the stars within it. From our estimations there is not enough mass to keep the galaxy together. Therefore there must be mass we cannot detect. This is dark matter.
44
What force is carried by a photon?
Electromagnetic Force
45
What represents a magnetic field coming 'out of the page'?
A dot
46
How is a p-n junction connected in forward bias?
Connect n-type to negative of supply connect p-type to positive of supply
47
What is the definition for time dilation?
Time dilation is the difference in a time interval as measured by an object moving relative to a stationary observer.
48
What two principles underpin the theory of relativity?
1. When two observers are moving at constant speeds relative to one another, they will observe the same laws of physics.
2. The speed of light (in a vacuum) is the same for all observers.
49
In the photoelectric effect, what happens to the maximum kinetic energy of an electron if the irradiance is increased?
Why?
* There is no effect on the maximum kinetic energy it remains the same.
* The energy of the incident photons (E = hf) is unchanged.
50
Explain how Hubble’s Law can estimate the age of universe.
Hubble’s observations show galaxies move away from each other and Earth in all directions. So the universe must be expanding. So if you could go back in time the galaxies etc. would be closer together, so if you go back to the point when all the galaxies were at one point, this would be the beginning of the universe. t=1/H0
51
How can an inelastic collision be identified?
Calculate the **total** kinetic energy before the collision and the **total** energy after the collision.
If the total kinetic energy before the collision is greater than the total kinetic energy after the collision then it is an inelastic collision.
52
Explain what a stationary observer would notice if a car with a siren on it was moving towards them.
Each wave front is emitted closer to the observer than the previous wave. So each wave front reaches the observer in less time than the previous wave. This causes the number of wave fronts arriving at the observer per second to increase. So the frequency the observer experiences is increased.
53
If a spectral line is bright - what des this tell you?
More electrons are making that energy level transition producing more photons of light with the same frequency.
54
Explain why a forward biased p-n junction conducts.
* Energy is supplied to the n-type material by the battery
* The effect of this is to reduce the potential difference of the electric field.
* The electrons in the conduction band of the n-type now gain enough energy to overcome the internal electric field and pass into into the conduction band of the p-type.
* The p-n junction will conduct.
55
For Doppler Effect calculations you use the following formula.
Describe when you should use the + and when you should use the - in the equation.
Sound source moving towards observer USE - as less time for waves to reach observer. Sound source moving away from observer USE + as more time for waves to reach observer.
56
From this energy level diagram, what type of material is being represented?
Semiconductor
57
In the photoelectric effect, if the frequency of the incident radiation is increased what happens?
The electrons ejected will have more kinetic energy, if the frequency is greater than the threshold frequency.
58
What would happen to your apparent weight if you were standing on a set of Newton scales and were in a lift that was accelerating upwards?
Your apparent weight would increase, It would be equal to your weight plus the force to cause the acceleration upwards.
59
What would happen to your apparent weight if you were standing on a set of Newton scales and were in a lift that was accelerating downwards?
Your apparent weight would decrease, It would be equal to your weight minus the force to cause the acceleration downwards.
60
Using a grating how can you increase the spacing between the maxima?
* Use a grating with a smaller slit separation.
* Use a source with a greater wavelength of light
* Move the screen further away
61
What are the main features of the Bohr model of the atom?
1. Positively charged central nucleus.
2. Electrons (negatively charged) are in discrete energy levels and do not radiate energy
3. When an electron makes a transition from one energy level to another a specific amount of energy is lost or gained
4. Each line in a spectrum is produced when an electron moves from one energy level to another.
62
When is the energy of the ionisation level?
0 Joules
63
Does a particle accelerator use a.c. or d.c. to create the electric field?
Explain why.
a.c.
This is because the electric field must change direction every time a particle completes a half circle (Dee) to keep the accelerating potential in the correct direction for the particles motion.
64
What 2 conditions are required for nuclear fusion?
* High Temperatures
* High Pressure
65
Explain how a pure semiconductor conducts.
Conduction band is empty. Valence band is full. There is a small energy gap. If the temperature is increased the electrons in the valence band can gain enough energy to jump the gap into the conduction band. These electrons are free to move and so conduction increases.
66
In the equation E = mc2 , what does the m stand for?
The mass which is converted into energy, which is the difference in mass of the particles before the fission/fusion reaction and the mass after.
67
What is the definition for Conservation of energy?
Energy cannot be created or destroyed, only converted from one form to another.
68
Why does the photoelectric effect give evidence for light to be considered as a particle?
* Photoelectric effect cannot be explained if light is thought of as a wave or any light would cause photoemission if it shone on the surface long enough to deliver enough energy to the electrons..
* Each photon contains a discrete amount of energy which results in one photon ejecting one electron
69
How is a p-n junction connected in reverse bias?
Connect n-type to positive of supply Connect p-type to negative of supply
70
What is the definition for redshift?
Redshift of light - Light from stars or galaxies moving away from us is shifted to longer wavelengths and so the redder wavelengths of the spectrum.
71
What is the difference between a vector and a scalar?
Scalar requires size / magnitude only Vector requires size / magnitude and a direction
72
Describe the electric field around a positive charge.
Field lines away from the positive charge.
73
What is calculated from the area under a speed-time graph?
Distance travelled
74
A triangular prism can be used to split white light into a spectrum. Why does this occur?
Different frequencies/colours have different refractive indices.
75
Why is the abundance of helium and hydrogen in the universe evidence for the Big Bang?
Big Bang Theory says that matter started as a very simple form that became more complex as time passed. The simplest elements would have formed first and existed in larger quantities than heavier elements, which would not exist until stars are born. These first elements were hydrogen and helium. The fact that there is an abundance of these elements in the universe supports the theory.
76
Explain what happens to the reading on the voltmeter when the circuit is changed from figure 1 to figure 2.
Resistance in the circuit decreases.
Current in the circuit increases.
Lost volts will increase Vlost = Ir
E - Vlost = Vtpd
So the reading on the voltmeter will decrease as it measures the Vtpd.
77
What will increase the amount of diffraction?
* Longer wavelengths diffract more
* Narrower gaps cause more diffraction
78
What type of spectrum is this?
Line emission spectrum
79
What could be altered in the circuit below to decrease the charging time of the capacitor?
* Decrease the resistance of the resistor
* Decrease the capacitance of the capacitor
80
What is meant by irradiance?
The power per unit area
81
Describe the shape of a graph of voltage across capacitor against time for discharging a capacitor.
Starts from the supply voltage Decreases to 0V.
82
What is meant by an ideal source?
A source which has no internal resistance.
83
Explain what a stationary observer would notice if a car with a siren on it was moving away from them.
Each wave front is emitted further away from the observer than the previous wave. So each wave front reaches the observer in a longer time than the previous wave. This causes the number of wave fronts arriving at the observer per second to decrease. So the frequency the observer experiences is decreased.
84
What is meant by a **Hadron**?
Particles made from quarks
85
What is the period of a wave?
The time it takes one wave to pass a point.
86
What is irradiance?
The power per unit area
87
Explain Redshift
Explanation Light from distant galaxies and stars can be observed on Earth. These galaxies and stars are moving away from us. So each light wave front is emitted from slightly further away than the last. This causes the number of wave fronts arriving per second at the Earth to decrease. This is an apparent decrease in frequency, which results in an increase in the wavelength of the light we see on Earth. So the light is shifted to longer (more red) wavelengths. The frequency of the light emitted by the source does not change.
88
What is Newtons Second Law?
When an unbalanced force acts on an object it will accelerate.
89
Containment and cooling are issues associated with a nuclear fusion reactor. Why?
Temperature of the reaction is so high most materials will vaporise. So a magnetic field can be used to suspend the plasma away from the sides of the container.
This requires strong magnetic fields produced by superconducting coils. These only work at cery low temperatures so need good cooling systems.
90
What is the definition for EMF?
The number of Joules of energy given to each Coulomb of charge passing through the cell.
91
When will length contraction become apparent?
The stationary observer and a person or object moving at relativistic speeds experience length in the same way. Only when they compare the lengths they have experienced do they notice a difference. The person who is stationary will have experienced a shorter length in comparison.
92
In which mode is this operating?
Photovoltaic
93
What are the fingers representing in the right hand rule?
1. First Finger - Field (Magnetic field)
2. SeCond finger - Current
3. THumb - Thrust (Movement)
94
What can be said when comparing Vrms to Vpeak?
Vpeak is always greater than the Vrms
95
What evidence is there that Cosmic Microwave Background Radiation supports Big Bang Theory?
• It is the dominant source of radiation in the Universe • It is very uniform throughout the Universe. • It shows the characteristics of blackbody radiation. • It has a temperature of approx. 3K (2·74K) due to cooling on expansion of the universe. • CMBR is thought to be the “afterglow” of the Big Bang, cooled to a faint signal in the microwave region.
96
What is the photoelectric effect?
The photoelectric effect is when electromagnetic radiation is directed at a metal surface and ejects electrons from the surface.
97
Why does Redshift support Big Bang Theory?
Redshift occurs because galaxies are moving away from us. This is the continued expansion from the Big Bang. If the galaxies were not moving away the light would not experience redshift.
98
What force is carried by W and Z bosons?
Weak force
99
From this energy level diagram, what type of material is being represented?
Conductor
100
From the graph, how do you find the short circuit current?
When the Potential difference = 0V. Find this point on the graph, read off the corresponding current.
101
What is beta (minus) decay?
Beta (minus) decay is when a neutron decays into a proton releasing an electron and an antineutrino.
102
What will a moving charge experience in a magnetic field?
A force
103
What is the definition of 1 amp?
1 Coulomb of charge passing a point in 1 second.
104
What did beta decay provide the first evidence for?
The existence of neutrinos.
105
Which of the following are scalars? Time, Momentum, Acceleration, Energy, Speed, Velocity, Displacement, Distance, Force
Scalars: Time, Energy, Speed, Distance
106
What is refraction?
The change in speed of light (and wavelength) as it enters a different material, this can result in a change in direction.
107
What is a **Boson**?
Bosons are force carrying particles.
108
When will a gold leaf electroscope discharge?
* It must be negatively charged
* It must have a zinc plate
* Ultraviolet light of a high enough frequency must be shone on the plate
* When the frequency of the ultraviolet light is above the threshold frequency
109
What is the **Standard Model**?
The Standard Model explains how the basic building blocks of matter interact, governed by four fundamental forces.
110
What is the Law of Reflection?
Angle of incidence = Angle of reflection
111
What information do you get from a chemical symbol, such as the one shown below?
**Top number** = Mass Number = number of protons and neutrons in the nucleus.
**Bottom Number** = Atomic Number = number of protons in the nucleus.
The letters are the chemical symbol which can be found on the periodic table.
112
What represents a magnetic field going 'into the page'?
A cross
113
Describe the electric field between a positive charge and a negative charge.
Field lines run from positive towards negative.
114
What is the definition for The Big Bang?
The Universe was initially in a hot and very dense state and then expanded rapidly.
OR
All the matter in the universe was in an unimaginably small volume, almost a point, and rapidly expanded.
115
What do absorption lines in the Sun's spectrum show?
Evidence for the composition of the upper atmosphere of the Sun.
116
The colour of a star tells us about it's surface temperature.This colour can be split into all the radiations being emitted producing a blackbody graph. What do the blackbody radiation graphs of stars tell us?
The temperature of stellar objects is related to the distribution of emitted radiation over a wide range of wavelengths. The hotter the object the shorter the peak wavelength emitted. A hotter star will emit more radiation per unit surface area per unit time than a cooler one. (If they are similar in mass, surface area etc)
117
Explain how a p-type semiconductor can be created.
The semiconductor has impurities added that have three electrons in its outer shell. These three do not completely fill the band. So there are electrons free to move in this band so conduction increases.
118
Describe the electric field around a negative charge.
Field lines towards negatively charged particle.
119
In the photoelectric effect, if the irradiance of the incident radiation is increased what will happen?
* No electrons will be ejected if the frequency of the incident radiation is below the threshold frequency.
* If the frequency is above the threshold frequency then more electrons will be ejected from the surface.
120
What is the frequency of a wave?
The number of waves per second.
121
What is the ground state?
This is the energy level with the least energy. It is the most negative energy level.
122
Give **one** advantage of producing electricity by nuclear fusion.
* Abundant fuel supply (Deuterium can be extracted from sea water)
* Safe (Small amounts of fuel, if reaction is unchecked it results in it stopping)
* Clean (No combustion so no air pollution)
* Less nuclear waste (waste is not high level weapons grade, needs stored for about 100 years)
* Efficient (1kg fusion fuel gives same energy as 10 million kg of fossil fuels)
123
What is the resultant of a number of forces?
the single force that would have the same effect as all the other forces OR the vector sum of all the forces
124
What evidence is there to support Big Bang Theory?
* Cosmic Microwave Background Radiation
* Explanation of Olber's Paradox (Why we see a dark sky)
* Abundance of hydrogen and helium in the universe
* Redshift of galaxies
125
What are the names of the 6 types of **Leptons**?
1. Electron
2. Electron neutrino
3. Muon
4. Muon neutrino
5. Tau
6. Tau Neutrino
126
What is the definition of Impulse
Force on an object multiplied by the time the force acts for OR the change in momentum of an object.
127
What is acceleration?
Rate of change of velocity OR change in velocity per second.
128
A ball is thrown upwards into the air and is allowed to fall and bounce. See graph.
At which points is the ball at the top of it's flight?
B, F
129
Describe the field lines between two negative charges.
The field lines run towards the negative charges but no filed lines between them.
130
What is Hubbles Law?
Hubble’s Law is the relationship between the recession velocity of a galaxy as it moves away from us and its distance.
131
What is velocity?
Rate of change of displacement
132
Describe the shape of a graph of current in a capacitance circuit against time for discharging a capacitor.
Starts from a maximum value and decreases to zero, current is in the opposite direction from the charging current.
133
What would happen to your apparent weight if you were standing on a set of Newton scales and were in a lift that was de-accelerating upwards?
Your apparent weight would decrease, It would be equal to your weight minus the force to cause the de-acceleration upwards.
134
What can be said about the Gravitational force?
It is always attractive.
135
Explain how an LED produces light.
* When the LED is forward biased. Energy supplied to the electrons in the n-type conduction band by the battery.
* The electrons now have enough energy to overcome the internal electric field and move through the electric field into the empty conduction band of the p-type semiconductor material.
* The electron then drops from the conduction band of the p-type to the valence band of the p-type.
* The electron gives out the energy as a photon of light as it drops into a lower energy band.
136
If white light is shone through a grating what does the interference pattern look like?
* The central order maximum will be white
* At every other maxima a spectrum will be produced
137
In a fusion reactor why are the high temperatures required a problem?
High temperature required to give the hydrogen atoms enough energy to overcome the electrical repulsion between the protons. This is difficult to contain as all materials would vaporise at this temperature.
138
A ball is thrown upwards into the air and is allowed to fall and bounce. See graph.
Between which points on the graph is the ball hitting the ground?
C-E, G-I
139
What are the names of the 6 types of **Quarks**?
1. Up
2. Down
3. Charm
4. Strange
5. Top
6. Bottom
140
Describe the field lines between two positive charges.
Field lines run away from the positive charges. No field lines between them.
141
What is capacitance?
The charge stored per volt.
142
A proton is made up of two up quarks and a down quark. The up quarks are both positively charged. Why does the proton not get torn apart?
Gluons carry the strong force to hold the quarks together. This strong force is greater than the force of repulsion between the particles.
143
How is the internal electric field/layer created in a pn junction?
* Electrons from the conduction band of the n-type move into the conduction band of the p-type and drop into the valence band of the p-type material.
* This leaves the n-type material slightly positively charged and the p-type material slightly negatively charged around the junction.
* This creates a potential difference which gives an electric field.
* The electrons in the conduction band of the n-type, do not have enough energy to overcome the potential difference of the electric field, to pass into the conduction band of the p-type.
144
Explain how a particle accelerator works.
1. Acceleration of charged particles - use an **electric field** which causes particles to experience a force and accelerates them.
2. Deflection of charged particles - **magnetic fields** are used to chage the direction of the moving charged particles.
3. Collision of charged particles - against a fixed target or between two beams of particles.
145
What is meant by absolute refractive index?
It is the ratio of speed of light in a vacuum to the speed of light in the material.
146
What is a **Fermion**?
It is a matter particle.
147
What is the definition of Conservation of momentum?
The total momentum before a collision is equal to the total momentum after a collision in the absence of external forces
148
Explain what would happen to your apparent weight if you were standing on a set of Newton scales and were in a lift that was travelling at a constant speed.
Your apparent weight would = real weight as the forces are balanced.
149
What is meant by a **Meson**?
Mesons are made from 2 quarks.
They always consist of a quark and an antiquark pair.
150
What is the difference between speed and velocity?
Speed is distance divided by time OR rate of chage of distance Velocity is the displacement divided by time OR rate of change of displacement, with a direction
151
What is the effect of an electric field on a charged particle?
The particle will experience a force that causes an acceleration.
152
What is a fundamental particle?
A fundamental particle is one that cannot be broken down into any sub particles.
153
If an unstable nucleus undergoes alpha decay what is given out and what is the effect on the mass number and the atomic number?
An alpha particle is a helium nucleus.
**Mass Number -** This means that the product mass number + the mass number of a helium nucleus = mass number of the original unstable nucleus.
**Atomic Number** - This means that the product atomic number + the atomic number of a helium nucleus = atomic number of the original unstable nucleus.
154
What is meant by a **Baryon**?
Baryons are made from 3 quarks
155
What is the amplitude of a wave?
The distace from the centre of a wave to the crest or trough.
156
Explain how a satellite remains in orbit.
The satellite has a constant horizontal velocity and a constant vertical acceleration due to the gravitational field strength. The planet curves away from the satellite as it falls.
157
What is speed?
Rate of change of distance
158
What are the 4 differences in spectra produced by refraction (in a prism) and by a grating?
Prism Grating
One spectrum Many spectra
Produced by Refraction Produced by interference
Red light deviated least Red light deviated most
Spectrum is dim Spectrum is bright
159
A brick is dropped first onto concrete then onto a sponge surface. The same brick is dropped and it is dropped from the same height. On which surface does the brick exert the smallest force?
As the brick is dropped from the same height, it will start from rest in both cases and reach the same speed before it hits the surface. The change in momentum remains the same, mv-mu. The time of contact will increase on the spongy surface. Ft = mv-mu So the **average force** will decrease.
160
Describe the shape of a graph of current in a capacitance circuit against time for charging a capacitor.
Starts from a maximum value and decreases to zero.
161
What is meant by diffraction?
Diffraction is the bending of waves round an object.
162
What evidence is there for antimatter?
**Positrons** discovered ocurring naturally in cosmic rays.
163
What is the threshold frequency?
The **minimum** frequency of light required to eject an electron from a metal surface.
164
What is constructive intereference?
This occurs when two waves meet at a point in phase.
165
What is the ionisation level?
This is the energy needed by an electron to leave the atom altogether.
166
Why were neutrinos suggested as an extra particle produced as a result of beta decay?
When beta decay occurs momentum and energy should be conserved. This was not happening if only the proton and beta particle were considered. There had to be another particle that carried the rest of the energy away.
167
What does the Doppler effect apply to?
All waves
168
What will a stationary charge create?
An electric field
169
What is the short circuit current?
The maximum current a supply can give - this is achieved when the terminals of the supply are joined with a short thick wire ( almost no external resistance)
170
What is the test for a wave?
If it can cause interference.
171
What will a moving charge create?
1. An electric field
2. Magnetic field
172
What type of spectrum is this?
Line absorption spectrum
173
Explain how an n-type semiconductor can be created.
The semiconductor has impurities added that have five electrons in its outer shell. Four of these are used to fill the valence band. The fifth electron is in the conduction band. This is free to move and so conduction increases.
174
What is a maxima?
A point where constructive interference occurs.
175
What type of spectrum is this?
Continuous spectrum
176
Which two units can be used for momentum?
Ns OR kgms-1
177
What is the definition for electric field strength?
The electric force per unit charge acting at a point in the field.
178
What formula is used to work out the component of weight parallel to the slope?
F = mgsinØ
179
What is gravitational field strength?
The force due to gravity per unit mass (kg)
180
Which of the following are vectors? Mass, Weight, Momentum, Impulse, Work, Temperature, Acceleration, Velocity, Speed
Vectors: Weight, Momentum, Impulse, Acceleration, Velocity
181
What is the definition for length contraction?
Length contraction is the difference in length (in the direction of motion) of an object moving relative to a stationary observer. Length contraction only takes place in the direction that the object is travelling.
182
What is the evidence for dark energy?
Distant objects are accelerating away from us. There must be something to overcome the gravitational forces acting. The extra energy that these objects gain is called dark energy.
183
Describe the field lines between parallel plates.
Field lines run from positive to negative plates.
184
What is the definition for a potential difference of 1 Volt?
There is a potential difference of 1 Volt between two points if I joule of energy is required to move 1 coulomb of charge between the two points.
185
What could be altered in the circuit below to increase the charging time of the capacitor?
* Increase the resistance of the resistor
* Increase the capacitance of the capacitor
186
What is a minima?
A point where destructive interference occurs.
187
In the following circuit what quantity will the voltmeter measure and why?
The Vtpd as there is a complete circuit and current is flowing so, some voltage will be lost.
188
From the graph, how do you find the EMF ?
When the current = 0A. Find point on graph where current = 0A, read off corresponding voltage.
189
What is the value of the mains supply?
230V, 50Hz
190
Describe the shape of a graph of voltage across capacitor against time for charging a capacitor.
Starts from 0V. Increases to the supply voltage.
191
What can be calculated from the area under a Force - time graph?
Impulse OR Change in momentum
192
How does an antimatter particle compare with a matter particle?
Antimatter particle has similar properties to the matter particle but **equal and opposite charge**.
193
At what speeds would you have to take relativistic effects into account?
For small velocities i.e. less than 0.1 times the speed of light relativistic effects are negligibly small.
194
What assumption is made when calculating the Gravitational force?
The objects are spherical
195
In physics what is meant by a **field**?
It is the region where an object experiences a force.
196
What is meant by the Root Mean Square Voltage? (Vrms)
It is the value of an AC voltage that will deliver the same amount of energy as a DC voltage.
197
Give one application for Hubbles Law
Calculating the age of the universe
198
What is destructive interference?
Destructive interference occurs when two waves meet at a point exactly 180O out of phase.
199
What can you say about electrons absorbing photons in the photoelectric effect?
* An electron can only absorb the energy from one photon
* The electron absorbs all the energy from the photon.
200
What causes a projectile to follow a curved path?
The projectile has a constant horizontal velocity and a constant vertical acceleration due to the gravitational field strength.
201
What is Olber's Paradox?
Olber said that if the universe was infinitely old and static that we should see stars in all directions. But the universe is not infinitely old it had a beginning (so light from distant stars may not have had time to reach us yet) and the universe is expanding (galaxies are moving away from us so the light may be redshifted into the infra-red part of the spectrum so we will not see the light).
202
A ball is thrown upwards into the air and is allowed to fall and bounce. See graph.
Between which points on the graph is the ball travelling upwards?
A-B, E-F,
203
Explain how a photovoltaic cell produces an electric current.
* A photon is absorbed by an electron in the valence band of the p-type material.
* If this energy is high enough the electron can jump into the conduction band of the p-type.
* The electron experiences a force from the internal electric field.
* The electron is moved through the electric field to the conduction band of the n-type.
* This creates a current.
204
Give two sources of EMF
* chemical cell
* Thermocouple
* Piezo-electric generator
* Solar cell
* Electromagnetic generator
205
From this energy level diagram, what type of material is being represented?
Insulator
206
What are the two types of **Fermions**?
Quark
and
Lepton
