Main Flashcards
1
Q
What are the benefits of using electrostatically charged spray paint?
A
Paint has same charge so repels = fine mist, no clumps. Object has opposite charge, attracts paint into corners and around the back
2
Q
What are the advantages of wind power?
A
Renewable,no air pollution,low running costs, no fuel costs
3
Q
What sort of electricity is needed to make transformers work?
A
AC; current must change direction so magnetic field keeps changing direction
4
Q
Equation: kinetic energy, mass and speed
A
kinetic energy = ½ x mass x speed²
5
Q
What is another name for the rate of flow of charge?
A
Current
6
Q
Equation: energy transferred and work done
A
energy transferred = work done
7
Q
Time
A
second, s
8
Q
Describe the arrangement and motion of particles in a liquid
A
Irregular pattern;Able to move over/past other particles;Little space between particles;
9
Q
Equation: pressure, force and area
A
pressure = force ÷ area
10
Q
Resistance, R
A
ohm (Ω)
11
Q
Factors which affect braking distance
A
Speed, weight of vehicle, quality of brakes and tryes, road surface
12
Q
gravitational potential energy, mass, g and height
A
gravitational potential energy = mass x g x height
13
Q
Give a use for x-rays
A
looking at the insides of things (medical imaging and other objects)
14
Q
What does work done = energy transferred mean?
A
If you do 10J of work on a system you transfer 10J of energy to it.
15
Q
What is the frequency range for human hearing
A
20 Hz - 20 000 Hz
16
Q
What is the role of the moderator in a nuclear reactor?
A
To slow neutrons down so that they can cause new fissions
17
Q
What particle do control rods absorb?
A
Neutrons
18
Q
The gradient of a distance-time graph gives
A
Speed
19
Q
Equation: pressure difference, height, density and g
A
pressure difference = height x density x g
20
Q
What are the artificial sources of background radiation?
A
Medical sources, fallout from nuclear weapons testing and use, nuclear accidents
21
Q
Mass, m
A
kilogram (kg)
22
Q
Velocity
A
metre per second, m/s
23
Q
If you double the volume of a sealed container of gas (at a constant temperature) what happens to the presure?
A
Pressure will halve
24
Q
When investigating the relationship between pressure and volume what two quatities must you keep constant?
A
Temperature and mass of gas must be kept constant when investigating pressure and volume
25
Density, ρ
kilogram per metre cubed (kg/m³)
26
The initial linear part of a force-extension graph is linked to what law?
Hooke's Law (Force is directly proportional to extension)
27
What is the law of reflection?
Angle of incidence = Angle of reflection
28
How can you prevent heat transfer by radiation?
Shiny surfaces are poor emitters. They also refelect the thermal radiation back.
29
What is the critical angle
When ligh hits the boundary at the critical angle the angle of refraction is 90°
30
Wavelength, λ
metre (m)
31
Comets orbit what? What shapes are their orbits?
Comets orbit stars (e.g. the Sun) in elliptical orbits
32
average speed, distance and time
speed = distance ÷ timeaverage speed = total distance ÷ total time
33
The area under a velocity-time graph gives
Distance travelled
34
Pressure
pascal, Panewton per metre², N/m²
35
How would you find the volume of a regular object (e.g. a cube of metal)
measure each side (with ruler) and multiply together
36
What happens when current flows through a resistor
When current flows through a resistor it heats up (this effect is used in kettles and toasters etc.)
37
When a magnet moves through a coil of wire what happens?
A magnet moving through a coil causes a current to flow
38
How can you increase the amount of voltage which is induced when moving a magnet into a coil?
Stronger magnet, move magnet faster
39
Name some electrical conductors (low resistance, allow current to easily flow)
Metal, graphite
40
When the angle of incidence is greater than the critical angle light is…
Totally internally reflected
41
Describe how thermal energy is transferred by radiation
Thermal radiation is an electromagnetic wave.
42
kilo
1 000
43
Name some vector quantities
Velocity,displacement,acceleration,force,momentum,moment,current
44
Why is a current induced in the secondary coil?
The secondary coil sees a changing magnetic field;electrons experience a force and move;which induces a current
45
Why is iron used as the core for a transformer?
Soft magnetic material; gains and loses magnetism easily.
46
What is the principle of conservation of energy
Energy cannot be created or destroyed; only changed from one form to another.
47
Magnets can attract or repel?
Other magnets
48
How is electricity generated in a generator?
A large coil is spun in a strong magentic field, this causes a force on the electrons and makes them flow producing a current.
49
Temperature, T
kelvin (K)
50
What happens to the resistance of a thermistor as it is heated
High temperatures reduces the resistance of a thermistor
51
Equation: charge, current and time
charge = current x time
52
What are the disadvantages of solar heating systems?
Unreliable (doesn't work at night),may need additional boiler to produce hot water
53
What is Newton's third law?
If object A exerts a force on object B, object B exerts an equal and opposite force on object A
54
Why do different planets have different values of g (gravitational field strength)
Planets with more mass (e.g. Jupiter) have a higher value of g
55
Equation: acceleration, change in velocity and time taken
acceleration = change in velocity ÷ time taken
56
What type of radioactive decay is most penetrating?
Gamma
57
gravitational potential energy, mass, g and height
gravitational potential energy = mass x g x height
58
What is felt when a current-carrying wire is in a magnetic field?
A force is felt when a wire carries a current in a magnetic field
59
Equation: work done, force and distance moved
work done = force x distance moved
60
weight, mass and gravitational field strength
weight = mass x gravitational field strength
61
Equation: primary voltage, secondary voltage, primary turns and secondary turns
primary voltage ÷ secondary voltage = primary turns ÷ secondary turns
62
Time, t
second (s)
63
Force
newton, N
64
Equation: force, mass and acceleration
force = mass x acceleration
65
What equation links momentum, mass and velocity?
Momentum = mass x velocity
66
What is the order of the EM spectrum
Radio, Microwave, Infra-red, Visible, Ultra-violet, X-ray & Gamma
67
How can you see the shape and direction of a magnetic field
Use plotting compasses
68
How would you find the volume of a small irregular object (e.g. a pebble)
submerge in water. The volume of water displaced = volume of pebble
69
Natural satellites (e.g. moons) and artificial satellites (e.g. Hubble) orbit what?
Planets
70
A galaxy is made up of…
Billions of stars
71
Equation: input current, input voltage, output current and output voltage
input current x input voltage = output current x output voltageIIVI = IOVO
72
How does a stretching seatbelt reduce injury
Increases collision time, lower deceleration (a=V/t), lower force (F=ma)
73
milli
1/1 000
74
Equation: charge, current and time
charge = current x time
75
How does a fuse work
When the current goes higher than the value of the fuse it melts. This breaks the circuit and stops current flowing
76
What happens to particles at absolute zero? What is the pressure? Why?
Paricles stop moving at absolute zero (no KE), pressure is zero as particles are not colliding with walls
77
Electrical hazards include….
Frayed cables, damaged sockets, water near sockets and metal objects in sockets
78
Mass
kilogram, kg
79
What part of the EM spectrum has the highest frequency (and energy)
Gamma has the highest frequency
80
What are the advantages of fossil fuels?
Reliable (not weather dependent),already established,high power output
81
What are the advantages of nuclear power?
Reliable (not weather dependent),already established,high power output
82
What are the energy transfers involved with nuclear power
nuclear ⇒ thermal ⇒ kinetic ⇒ electrical
83
What is the efficiency of this machine
useful output energy = 10Jtotal input energy = 100Jefficiency = 10/100= 0.1 or 10%
84
Density
kilogram per metre cubed, kg/m³
85
Area
metre squared, m²
86
Force, F
newton (N)
87
Give some useful uses of electrostatic charges
Paint spraying,Chimney precipitator (smoke cleaner),Photocopier,Ink Jet Printer
88
Frequency
hertz, Hz
89
Describe the arrangement and motion of particles in a solid
Regular pattern OR close packed;Vibration in position;Little space between particles
90
Volume, V
metre cubed (m³)
91
What are the disadvantages of nuclear power?
Produces long lasting radioactive waste which must be securely stored,mining hazardous
92
What part of the EM spectrum has the longest wavelength
Radio has the longest wavelength
93
What happens to the average speed of gas molecules as you heat a gas?
Average speed of gas molecules increases as you heat a gas
94
efficiency, useful energy output and total energy input
efficiency = useful energy output ÷ total energy input (also efficiency = useful energy output ÷ total energy output)
95
What are the general disadvantages of renewable sources of power?
Unreliable (weather dependent),large amount of land needed to replace a typical power station
96
Describe a transverse wave and give an example
Transverse waves travel at right angles to the oscillation which caused them. E.g. light, other EM waves, Mexican Waves
97
After two half-lives, how much of an original sample is left?
One quarter
98
What is the difference between scalar and vector quantities?
Vectors have a direction as well as a magnitude (size)
99
What happens to the resistance of an LDR as more light is shone on it?
Bright light reduces the resistance of an LDR
100
Equation: voltage, current and resistance
voltage = current x resistance
101
Mega
1 000 000
102
Wavelength
metre, m
103
How can magnetism be induced in a magnetic material?
Placing a magnet close to a magnetic material will induce magnetism in the magnetic material
104
List the 4 types of stored (potential) energies
Gravitational, Elastic, Nuclear, Chemical
105
Define the time period of a wave
Time period is how long it takes for a wave to pass a point
106
What has the following magnetic field shape?
Field around a current carrying wire
107
How can you find the frequency of a sound wave from an oscilloscope trace
Measure time period T (of one wave) Use f = 1/T (careful with milli seconds) e.g T = 3ms so f = 1/0.003 = 333Hz
108
What are the advantages of geothermal power?
Renewable,no air pollution,low running costs, no fuel costs
109
What type of radioactive decay is most ionising?
Alpha
110
Equation: pressure, force and area
pressure = force ÷ area
111
Equation: wave speed, frequency and wave length
wave speed = frequency x wave length
112
Equation: refractive index, angle of incidence, angle or refraction
n = sin i ÷ sin rrefractive index = sin (angle of incidence) ÷ sin (angle of refraction)
113
How are electromagnets made?
A coil of wire around an iron core
114
Equation: density, mass and volume
density = mass ÷ volume
115
Why are step up and step down transformers used in the National Grid?
Voltage stepped up (e.g 100x);Current drops by the same amount (100x lower);less power loss due to heating;Stepped down to be safe in homes.
116
What materials does conduction happen best in and why?
Solids; particles are close together so can pass energy quickly. Works best of all in metals due to free electrons.
117
How can air molecules move heavy smoke particles (Brownian motion)
lots of tiny, fast moving air molecules exert enough force on a smoke particle to change its direction
118
What's wrong with -50K as a temperature?
You can't have negative kelvin temperatures, absolute zero (0K) is the coldest temperature possible
119
What change of state happens during freezing?
liquid to solid
120
Resistance
ohm, ?
121
Equation: moment, force and perpendicular distance from pivot
moment = force x perpendicular distance from pivot
122
In what two ways can radioactive decay be detected?
By photographic film and by a Geiger-Müller (GM) Tube
123
What is the atomic number?
The number of protons
124
What experiment can be done to demonstrate charging by friction?
Rub a plastic rod with a cloth, show charge on coulombmeter or repel/attract other charged things.Rub a balloon on jumper / hair stick to wall.
125
Acceleration
metre per second squared, m/s², m/s/s
126
Describe the motion of gas particles
gas particles move in a random fast motion
127
Length
metre, m
128
What makes something an elastic material
Material regains original shape once stretching force is removed
129
Equation: kinetic energy, mass and speed
kinetic energy = ½ x mass x speed²
130
Our local galaxy is called
The Milky Way
131
Maximum diffraction happens when the gap size is?..
similar to the wavelength
132
Describe a longitudinal wave and give an example
Longitudinal waves travel parallel to the oscillation which caused them. E.g. sound
133
What is the difference between Alternating Current (AC) and Direct Current (DC)
DC (direct current) only flows in one direction. AC (alternating current) constantly changes direction.
134
Explain parallel circuits
Several routes for current to take, allows components to be switched on individually (e.g. lights at home), components get full supply voltage
135
How does bending you knees help prevent injury?
Increases collision time, lower deceleration (a=Δv/t), lower force (F=ma)
136
What are the disadvantages of hydroelectric power?
Floods a large area,disrupts people and animals
137
Magnetically hard materials....
Are difficult to magnetise but keep their magnetism
138
Waves transfer ……………………………… without transferring ……………………….
Waves transfer energy and information without transferring matter
139
List the 5 types of non stored energies
Light, sound, thermal, kinetic, electrical
140
Give a danger and use for infra red
Danger = skin burns,Use = cooking and night vision equipment
141
What type of radioactive decay emits a helium nucleus?
Alpha
142
Potential Difference, V
volt (V)
143
After four half-lives, how much of an original sample is left?
One sixteenth
144
Radioactive activity, A
becquerel (Bq)
145
weight, mass and gravitational field strength
weight = mass x gravitational field strength
146
The frequency of a sound wave is linked to its?.
pitch
147
Charge, Q
coulomb (C)
148
What is the nature of an electric current in a metal conductor?
A flow of negatively charged electrons flowing from the negative side of a battery or power supply
149
What happens to the current in a circuit when the resistance is decreased?
Current increases as resistance decreases
150
How can you show current is flowing in a circuit
A bulb or LED will light when a current flows. Or use an ammeter (in series)
151
Equation: refractive index, angle of incidence, angle or refraction
n = sin i ÷ sin r
152
wave speed, frequency and wave length
wave speed = frequency x wave length
153
Give a use for visible light
Seeing, optical fibres, photography
154
What are the energy transfers involved with fossil fuels
chemical ⇒ thermal ⇒ kinetic ⇒ electrical
155
Equation: energy transferred and work done
energy transferred = work done
156
Radioactive activity
becquerel, Bq
157
What are the natural sources of background radiation?
Radon gas, cosmic rays, the ground, food and drink
158
What happens to the pressure acting in a fluid as you go deeper?
pressure increases as you go deeper into a fluid
159
voltage, current and resistance
voltage = current x resistance
160
Why does an object reach terminal velocity?
As the speed and drag increase, eventually weight = drag so no resultant force
161
Give an example of an AC source and a DC source
Mains are an AC source. Batteries are DC sources
162
moment, force and perpendicular distance from pivot
moment = force x perpendicular distance from pivot
163
Why doesn't DC work for transformers?
DC doesn't change direction so the magnetic field is constant
164
refractive index and critical angle
n = 1 ÷ sin crefractive index = 1 ÷ sin (critical angle)
165
Frequency, f
hertz (Hz)
166
Potential Difference
volt, V
167
What isotope Carbon-14 often used for
radiometric dating; identifying how old something is based on the count rate of the carbon-14
168
Give a danger and use for ultra violet
Danger = blindness and damage to surface cells,Use = flourescent lamps, security markings
169
Acceleration, a
metre per second squared (m/s/s, m/s²)
170
What happens to the current in series circuit as more bulbs are added?
More bulbs in series increases the resistance and decreases the current
171
What is produced around a conductor when electrical current flows?
An electromagentic field is created when current flows
172
How would you describe a uniform field (3 marks)
Field lines are straight, parallel and equally spaced in a uniform field
173
What is the relationship between input and output power of a transformer?
Pprimary = PsecondaryIpVp = IsVs
174
What are circuit breakers
Circuit breakers break the circuit when the current goes higher than a certain value. Unlike fuses, they can be reset once tripped.
175
What type of radioactive decay can only be stopped by a few centimetres of lead?
Gamma
176
What particle was fired at gold foil during Rutherford's experiments. What charge did it have?
Alpha particle which has a positive charge
177
Name some electrical insulators (high resistance, do not allow current to flow)
Plastic, wood, (pure) water
178
Volume
metre cubed, m³
179
If a car has 20 000J of kinetic energy, how much work do the brakes have to do to stop the car?
20 000J
180
Equation: force, mass and acceleration
force = mass x acceleration
181
The universe is made up of….
Billions of galaxies
182
How can you prevent heat transfer by convection?
Trap the fluids (e.g. trapping air in wool). This prevents both conduction and convection.
183
Equation: pressure difference, height, density and g
pressure difference = height x density x g
184
After three half-lives, how much of an original sample is left?
One eighth
185
How do radiators in your house heat a room (hint, not by radiation)
Radiators heat air which rises and produces a convection current. Cold air is drawn into the bottom of the radiator too.
186
Power
watt, W
187
What type of radioactive decay does not emit a particle?
Gamma
188
Which support provides more force? Why?
Moments about the box are equal. A closer to box, so needs bigger force to provide same moment as B.
189
Momentum
kilogram metre per second, kgm/s
190
How do you convert from C to K?What is 20 °C in K?What is -40 °C in K?
Add 273,20 °C + 273 = 293 K,-40 °C + 273 = 233 K
191
What materials does convection happen best in and why
Fluids (gases and liquids); particles must be free to move so can't happen in a solid
192
If an object has 100J of gravitational potential energy when on a shelf and falls off, how much kinetic energy does it have just before hitting the floor? What have you assumed?
100J. But we assume there is no air resistance (100% efficient)
193
Why aren't machines 100% efficient?
Typically some energy is lost to the surroundings as heat.
194
Pressure, p
pascal, newton per metre (Pa, N/m²)
195
Define frequency
Frequency is the number of waves going past a point per second
196
Moment
newton metre (Nm)
197
When the angle of incidence is less than the critical angle light is…
When the angle is less than the critical angle, light is refracted
198
Describe the structure of a transformer
Two coils of wire wrapped around a laminated iron core
199
How does convection produce wind?
Air is heated, expands, becomes less dense, rises, colder air rushes into the area of low pressure.
200
Describe how thermal energy is transferred by conduction
Particles knock into each other and pass on the energy
201
How can fires be prevented when refuelling aircraft (linked to electrostatic charge)
Attach Earthing strap (to discharge aircraft) before beginning to refuel
202
Velocity (initial, final), (u,v)
metre per second (m/s)
203
What are the disadvantages of solar cells?
Unreliable (doesn't work at night or when cloudy),large area needed to replace a typical power station,inefficient
204
Give a use for radio
Communictions and broadcast
205
What are the energy transfers involved with solar heating systems
thermal ⇒ thermal
206
efficiency, useful energy output and total energy input
efficiency = useful energy output ÷ total energy input
207
Power, P
watt (W)
208
What happens to the speed of an object as it falls?What happens to its drag?
Speed increases (resultant force downwards)drag increases
209
Which way does light bend when it enters a material with a higher refractive index (e.g. air to glass)
Light bends towards the normal when it goes from air to glass
210
What are the advantages of solar heating systems?
Renewable,no air pollution,low running costs, no fuel costs
211
The rate of doing work is also known as?
Power
212
The amlitude of a sound wave is linked to its?.
volume
213
Length, l
metre (m)
214
Explain series circuits
Only one loop, simple, if one component fails no current flows
215
What are the disadvantages of wind power?
Unreliable (only works when windy),needs lots of land,visual pollution, a large number needed to replace a typical power station
216
How can you produce a uniform magnetic field (3 marks)
Place two attracting bar magnet poles (N&S) close together, hold them in place to avoid them touching
217
What change of state happens during condensing?
gas to liquid
218
Give a danger and use for gamma
Danger = cancer, mutation,Use = sterilising food and medical equipment
219
What are the disadvantages of geothermal power?
Only works in very specific places,deep drilling difficult and expensive
220
Moment
newton metre, Nm
221
Refraction is when a wave………………………..
...bends
222
What change of state happens during melting?
solid to liquid
223
What can happen to waves when they pass an edge or go through a gap?
Diffraction; waves spread out
224
Forces can do what to an object?
Change speed, shape or direction
225
What is the difference between analogue and digital signals
Analogue signals can have any value.Digital signals can ONLY be on or off
226
What are the disadvantages of fossil fuels?
Release CO₂ and air pollution, mining hazardous
227
When a wave is refracted what two things change
Speed and direction change during refraction
228
Equation: momentum, mass and velocity
momentum = mass x velocity
229
One Watt is equal to what?
1 watt is 1 joule per second
230
What are the energy transfers involved with wind power
kinetic ⇒ electric
231
What are the advantages of solar cells?
Renewable,no air pollution,low running costs, no fuel costs
232
What force is felt by the charged particle
No force felt as particle is moving parallel to field.
233
What is the easiest way to reduce risk of injury from microwaves, infra red, ultra violet or gamma
Avoid exposure
234
What change of state happens during boiling?
liquid to gas
235
Electric current
amp, A
236
Magnetically soft materials...
Are easy to magnetise but lose their magnetism quickly
237
Equation: work done, force and distance moved
work done = force x distance moved
238
Magnets can attract?
Magnetic materials (and other magnets too)
239
What type of radioactive decay can be stopped by a few centimetres of air?
Alpha
240
How can electrostatic charge be used to clean smoke in a chimney?
Smoke particles charged by wires and attracted to charged plates
241
What do the thumb and fingers represent when using Flemming's Left Hand Rule?
thumb = force (direction of movement),First Finger = Field,seCond finger = Current
242
Factors which affect thinking distance
Speed, awareness (tired, alcohol)
243
What type of radioactive decay emits an electron?
Beta
244
centi
1/100
245
Temperature
kelvin, K
246
How can you prevent heat transfer by conduction?
Use insulators (such as air)
247
What are the energy transfers involved with solar cells
light ⇒ electrical
248
Only appliances with what sort of case need an Earth wire?
Appliances with metal cases; if the live wire comes loose someone could get a shock without an Earth wire.
249
Time
minute, hour, day, min, h, d
250
How can you produce more electricity in a generator?
Stronger magnet, spin coil faster
251
How can you increase the speed of a motor (or volume of a speaker)?
Stronger magnet, more current
252
What types of radioactive decay do not change an isotope's mass number?
Beta and Gamma
253
Why is the image in a mirror virtual?
The image in a mirror can't be projected onto a screen
254
How can you visualise the shape of a magnetic field (3 marks)
Place magnet under paper, sprinkle iron filings on top of paper, gently tap paper so filings line up with field lines.
255
Do isotopes have the same atomic number, or the same mass number?
Atomic number (number of protons)
256
What is the relationship between force and extension for a spring
Force is directly proportional to extention (if force doubles extension doubles)
257
Describe the arrangement and motion of particles in a gas
No pattern;Able to move freely/fast;Larger space between particles;
258
What two pieces of equipment are needed to display a sound wave?
Microphone and oscilloscope
259
Why is the iron core in a transformer laminated?
Prevents eddy currents;stops heating;keeps efficiency high.
260
How does a material gain a positive electrostatic charge?
Object loses electrons to gain a positive charge
261
How do gas particles exert pressure on a container
molecules collide with walls of container,exert a force,over a given area,pressure = force / area
262
One volt is equal to one?..
One joule per coulomb
263
What is double insulation
Appliances with plastic cases are double insulated; even if live wire comes loose inside, a user can't be shocked
264
Equation: refractive index and critical angle
n = 1 ÷ sin c
265
Planets orbit what? What shape are their orbits?
Planets orbit stars (e.g. the Sun) in circular orbits
266
Energy, E
joule (J)
267
What type of radioactive decay can be stopped by a sheet of paper?
Alpha
268
Charge
coulomb, C
269
Where does an objects weight always act
Through its centre of gravity
270
How can electrostatic charge cause a fire at a petrol station.
Charge builds up on car while drivinga spark when person touches car+ fuel vapour = explosion
271
How do you convert from K to C? What is 300K in °C?What is 100K in °C?
Subtract 273,300K-273 = 27 °C,100K-273 = -173 °C
272
When two objects with a positive electrostatic charge are close together they?
Repel as like charges repel
273
Reflection is when a wave…………………………
...bounces off something
274
What are the advantages of hydroelectric power?
Renewable,no air pollution,low running costs, no fuel costs
275
More turns on the primary coil what sort of transformer?
Step down; voltage is bigger across the primary coil
276
What materials does radiation happen best in and why?
Transparent (see through) materials; thermal radiation can be absorbed by some materials and pass through others.
277
Name some scalar quantities
Speed,mass,volume,time,energy,charge,pressure,power
278
What has the following magnetic field shape?
Field around a flat coil(looks like an owl)
279
What is a magnetic field line?
A magnetic field line shows the direction of a magnetic field (N to S). Where lines are close together the field is strong.
280
A charged partical experience no force due to a magnetic field when?
Moving parallel to field
281
How can digital signals carry more information?
Multiplexing (e.g. different coloured light in fibre optics)Increase the frequency of the transmitter
282
How does a material gain a negative electrostatic charge?
Object gains electrons to gain a negative charge
283
What type of radioactive decay can only be stopped by a few millimetres of aluminium?
Beta
284
average speed, distance and time
speed = distance ÷ timespeed = distance⁄time
285
When a gas or liquid is at rest, what can you say about the pressure?
at a given depth, pressure in a fluid at rest acts equally in all directions
286
Energy
joule, J
287
Energy transferred per unit charge is known as?
Voltage
288
Electric current, I
amp (A)
289
What are the energy transfers involved with geothermal power
(nuclear) ⇒ thermal ⇒ kinetic ⇒ electric
290
Define wavelength
Wavelength is the distance between two peaks or two troughs
291
What are the dangers of ionising radiation?
Mutation and damage to cells and tissues
292
What is conservation of momentum?
Momentum before a collision (or explosion) is equal to the momentum after. Assuming no external forces act.
293
What is the mass number?
The total number of protons and neutrons
294
The gradient of a velocity-time graph gives
Acceleration
295
What has the following magnetic field shape?
Field around a solenoid (same shape as a bar magnet)
296
If the kelvin temperature of a gas doubles, what happens to the pressure it exerts?
Pressure doubles too
297
What are the energy transfers involved with water power
gravitational ⇒ kinetic ⇒ electric
298
When a wire is moved through a magnetic field what happens?
A wire moving through a magnet causes a current to flow
299
More turns on the secondary coil is what sort of transformer?
Step up; voltage is bigger across the secondary coil
300
Area, A
metre squared (m²)
301
What are the general advantages of renewable sources of power?
Renewable,no air pollution,low running costs, no fuel costs
302
Give a danger and use for microwaves
Danger = internal heating of body tissue,Use = cooking and satellite communications
303
What type of radioactive decay changes both an isotope's mass number and its atomic number?
Alpha
304
What is the role of the control rods in a nuclear reactor?
To control the rate of reaction by absorbing neutrons
305
What is the force which opposes motion
Friction (e.g. against a road) or drag (e.g. moving through air)
306
Describe how thermal energy is transferred by convection
Hotter regions of fluid expand, become less dense and float on colder regions
307
What happens to the pressure of a gas in a sealed container when you heat it? Why?
Pressure increases when you heat a sealed container of gas,molecules move faster hitting walls harder and more often,more force exerted on same area,pressure increases
308
density, mass and volume
density = mass ÷ volume
309
What is the relationship between kelvin temperature of a gas and average kinetic energy its molecules?
Kelvin temperature is directly proportional to average kinetic energy.Doubling the temperature (in kelvin!) doubles KE
310
What are some advantages of digital signals?
Can carry more informationEasier to clean the signal (remove noise)
311
Equation: acceleration, change in velocity and time taken
acceleration = change in velocity ÷ time taken
312
Define amplitude
Amplitude is the maximum displacement above the equilibrium
