Physics P2

Question 1

Different types of reflection

Answer 1

Specular (smooth surface)and diffuse(rough surface)

Question 2

What is rule for reflection

Answer 2

Angle of incidence is same as angle of reflection

Question 3

Description of S-waves and P-waves

Answer 3

S-wave is transverse(secondary doesn’t go through liquid )

P-waves is longitudinal (Primary does go through liquid longitudinal like ripples in liquids) and is quicker than s-waves

Question 4

What is the difference between a wave front diagram and a ray diagram

Answer 4

Wave front shows why the light refracts and changes direction by showing parts of the light slowing down
Ray diagram just shows the light reflecting and refracting

Question 5

What is the symbol for concave and convex lenses in a ray diagram

Answer 5

Convex line with two arrows at the end pointing away

Concave line with two arrows at the end pointing in

Question 6

What is the principle focus, focal length, lens axis in a concave and convex lens

Answer 6

Principle focus is where all the lines converge to in a convex lens and where the lines seem to come from in a concave lens

Focal length is the distance between the centre of the lens and the principle focus

Lens axis is the line going through the middle of the lens where if a light ray goes through it wont detract or change direction as the angle of incidence is 0

https://imgur.com/a/i1Yl9VB

Question 7

What does diminished mean in terms of lenses

Answer 7

Means image has gotten smaller
Opposite of magnified

Question 8

How do you draw a ray diagram

Answer 8

Draw a light ray from the top of image through the middle of the lens and axis

Draw another line from the top of the image parallel to the axis when it reaches the lens if convex it refracts towards the focal point if concave it follows the path of the focal point before the lens outward

The place the two lines meet is where the top of the real image is
If they don’t meet and are diverging then draw a dotted line going back and where the dotted lines meet is the top of the virtual image(where the image seems like it is coming from)

https://imgur.com/a/SjhOWDA

Question 9

Example of Non contact force

Answer 9

Magnetic force, electrostatic force, gravity

Question 10

Limit of proportionality

Answer 10

extension stops being proportional to force because it is inelastically deforming

Question 11

Units for density of liquid

Answer 11

kg/m^3

Question 12

What causes upthrust

Answer 12

When object is submerged in fluid a there is a force on it from every direction ,pressure increases with depth so force on bottom of the object is greater than force on top of an object that is submerged. The resultant force of this is upthrust

Question 13

What is upthrust equal to

Answer 13

Upthrust is equal to the weight of the fluid that’s been displaced

Question 14

Why will an object float or sink

Answer 14

If weight of object is more than upthrust it will sink, so if the weight of the object is more than the weight of the water displaced it will sink, so if density of object is more than density of water it will sink

Question 15

Why is there less air pressure higher you go

Answer 15

Less air particles above so less of their weight decreasing pressure
And air gets less dense higher you go up because of gravity. Density decreasing means less particles to collide and cause pressure

Question 16

What is Newtons first law

Answer 16

Object at rest stays at rest and object moving stays moving at constant speed unless force acted

Question 17

Newtons second law

Answer 17

F =ma
Means objects with higher mass need more force to accelerate
And means the acceleration is directly proportional to amount of force

Question 18

Newtons third law

Answer 18

Every action has opposite and equal reaction

Question 19

What is stopping distance and what effects it

Answer 19

Thinking distance
Distance car travels during drivers reaction time
Factors affecting it are
Factors effecting it are
Drugs
Alcohol
Speed
Distractions
Tiredness

Braking distance
Distance car travels while the brakes are applied
Factors effecting it
Speed
Road conditions
Tire conditions
Brake quality

Question 20

Units for momentum

Answer 20

(Kg m/s) m/s comes from velocity (p)in equations

Question 21

Safety features in cars and how they help

Answer 21

Crumple zones ,seatbelts, air bags they increase the amount of time to stop so the change in momentum during a crash is over a long time decreasing the force on the body at a given time decreasing the chance of injury

Question 22

How do you show the strength of magnetic field in a drawing

Answer 22

The more lines the stronger it is

Question 23

How to draw magnetic field drawing

Answer 23

lines looping around going from north to south and lines from north going outwards and lines from south going inwards

Question 24

How to know direction of magnetic field in wire

Answer 24

Use right hand thumb direction of current and fingers direction of magnetic field

Question 25

What is a solenoid

Answer 25

A coil of wire each individual magnetic field of the wires add up creating a stronger magnetic field

Question 26

What is motor effect

Answer 26

When wire carrying current is put through a magnetic field at 90 degrees it feels a force on it because of the interacting magnetic fields. If in parallel no force is exerted

Question 27

What effects the force on a conductor in a magnetic field

Answer 27

The current going through the wire Magnetic flux density Length of wire Can be seen in equation F = B I l

Question 28

How to know direction of force in motor effect

Answer 28

Flemings left hand rule thuMb Motion First finger Field SeCond finger Current

Question 29

How do motors work

Answer 29

Coil of wire in a spindle in a magnetic field Because the coil wraps around the current goes in two different directions meaning force is applied in two different directions causing it to spin the split ring make the contacts swap half way making motor rotate in the same direction

Question 30

How does a speaker work

Answer 30

Coil of wire attached to a paper cone, coil goes around a pole and is surrounded by the other pole . When a AC current is passed through the coil of wire it goes back and forth every time the direction of current switches moving the cone and displacing the air making sound. The frequency of the AC is the same as the frequency of sound the speaker makes

Question 31

What is the generator effect

Answer 31

When a conductor passes through a magnetic field and cuts them at 90 degrees a potential difference is induced and if the circuit is complete a current flows. If you move it back and forth the direction of the current changes making ac

Question 32

Difference between slip ring and slip ring commutator

Answer 32

Slip ring is 2 different rings with brushes the brush stays in contact with the split ring at all times. Used in alternator generators where it produces ac Slip ring is used in motors and dynamo generators. They are 2 half rings and the brushes change their connections with the slip rings every half turns. Used in motor to change direction of current in coil so it continues going the same direction. Used dynamos to create dc current

Question 33

What is the difference between alternator and dynamos

Answer 33

Alternator creates ac current because it doesn't have split rings commutator. Dynamo created dc because of its split rings commutator . The connections swap every half turn

Question 34

How does a microphone work

Answer 34

Diaphragm with coil attached different pressure waves move the diaphragm making the coil cut a magnetic field inducing an ac current through the coil.

Question 35

What is transformer used for and what does more turns mean

Answer 35

Increase or decrease voltage in AC current . The voltage is the same as the amount of turns, so if there is more turns in the secondary coil the voltage will be more if there is less turns in the secondary coil the voltage will be less

Question 36

Describe life cycle of a star

Answer 36

Starts off as a cloud of dust and gas called a NEBULAR Gravity pulls everything in and condenses it creating a protostar. In the PROTOSTAR the temperature rises and it gets more dense causing nuclear fusion to happen to hydrogen nuclei turning them into helium. Star is now in its MAIN SEQUENCE a long stable period where the force of gravity and the force of fusion are equal. Hydrogen begins to run out, for stars same size or smaller as the sun the star collapses inward making the temperature increase fusing helium nuclei into heavier elements up to iron then it swells up into a RED GIANT. The red giant becomes unstable and ejects its outer layer of dust and gas leaving a hot dense core called WHITE DWARF fusion isn't happening anymore so it starts to cool down into a BLACK DWARF If the the star is bigger than our sun when it runs out of hydrogen it turns into a RED SUPER GIANT and heavier elements are made up to iron. When fusion stops in the red super giant it explodes into a SUPER NOVA creating heavier than iron element and eject them out into space. The outside layer of gases in a super nova are blown away leaving the centre of the super nova which turns into a neutron star if the star is big enough it creates a black hole

Question 37

What is the correlation between speed and size of orbit

Answer 37

The smaller the orbit the higher the speed need to be for it to be stable since the force of gravity is stronger the closer you are you need higher speed to maintain your orbit

Question 38

Difference between geostationary and polar satellites

Answer 38

Geostationary orbit once per 24hr so they orbit the earth and are always pointing at the same place. They have a high orbit and orbit above the equator. Used for TV and communication Polar orbit satellites orbit in a shorter amount of time and orbit from pole to pole they have a lower orbit. Used to monitor the earth

Question 39

How does red shift prove the big bang

Answer 39

Light from other stars seem to be shifted towards the red spectrum meaning that they are moving away from us. Light from further away galaxy are more red shifted meaning they are moving away even faster so the unnerves is expanding meaning it had to start from a certain spot and expand out wards this is called big bang theory

Question 40

Role of dark matter and dark energy in big bang theory

Answer 40

The universe should slow down its expansion because of gravity but it is speeding up its expansion it is suggested dark matter and dark energy which cannot be detected is the cause of this

Question 41

What is CMBR

Answer 41

Microwave radiation that is in the whole universe believed the gamma radiation from the big bang has been stretched into microwaves

Question 42

What is a period of wave

Answer 42

The amount of time for a full cycle of wave to pass

Question 43

Describe water tank required practice

Answer 43

A tank of water 4 cm deep and a piece of white paper underneath and a lamp above. A vibrating bar creates waves in the water by placing a ruler on the paper you can measure the wavelength of 10 waves and then 1 wave can also use a camera to help. For frequency you can count the number of waves passing a point in 10 seconds and divide by 10.

Question 44

Describe sting wave RP

Answer 44

Attach one end of a string to a vibration generator and the other end to a hook with weights on it pass the string over a pulley. Turn on the vibration generator and change the frequency until a clear wave is visible. You can use a ruler to measure the wavelength each crest being half a wavelength and you know the frequency through the vibration generator

Question 45

Give names of EM spectrum

Answer 45

Radio waves, Micro waves, infra red, visible light, ultra violet, x-ray, gamma ray

Question 46

Describe refraction in terms of density

Answer 46

If density is higher when changing material it means the wave slows down making it bend towards the normal so the angle of incidence is more than angle of refraction If density is less it bends away from the normal so angle of incidence is less than angle of refraction

Question 47

Different types of radio waves

Answer 47

Long wave radio bends around the earth and can detract (bend) through stuff so it has a long range Short wave radio reflects of the ionosphere so has a long range

Question 48

Different uses of EM waves

Answer 48

Microwaves used to heat up food Microwaves for satellite communication Infrared for viewing the temperature of objects Visible light for optic fibre Ultra violet suntan X-ray imagery of bones Gamma rays medical tracer

Question 49

Difference between real and virtual image

Answer 49

Real image is where all the light rays converge creating an image on a screen Virtual image is when the light rays are diverging so you look at where the light rays seem to come from

Question 50

Hoe does distance from lens effect image

Answer 50

If object at 2F the image is inverted, real, same size If between F and 2F it is inverted, real, bigger If object is past F the object is right way up, virtual, bigger

Question 51

How do magnifying glasses work

Answer 51

Use convex lens, the image is closer than F so it creates a virtual, bigger, right way up image for the eye

Question 52

What does it mean to transmit light

Answer 52

Transparent objects transmit light because they let light through and don't absorb or reflect all the light

Question 53

Describe infrared RP

Answer 53

Place a Leslie cube on a heat proof mat and add boiling water. Wait for it to heat up, place a thermometer on all of its side and they will give the same value. Hold an infrared thermometer at a set distance(10 cm) form on side of the cube and take a reading. Do the same for the other sides. Repeat and calculate mean you should find that the black surfaces give out more infrared than the white surface and that matte surfaces give out more infrared than shiny surface

Question 54

Why is light emitted from hot objects

Answer 54

Every object emits EM waves because of it temperature normal objects emit infrared but when it gets hotter the wavelength changes and so does the intensity of the EM wave It eventually produces visible light form red hot to white hot to blue hot

Question 55

What is a perfect black body

Answer 55

Absorbs all the radiation that hits it so no radiation is reflected or transmitted It can also emit all of it radiation