physics exam questions

Question 1

why does different refraction happen at a boundary between air and glass?

Answer 1

• different parts of the wavefront enter glass at different times
• and the velocity is less in glass
• so one part of the wave front changes speed before other parts

Question 2

A student measured degrees of 6.0, 6.3, 6.4 and 5.8 from a 10 degree incidence angle - why should they have NOT recorded these results?

Answer 2

as the resolution of a protractor is 1 degree so it can’t be used to measure to 1dp

Question 3

Transformer X is used to transform power station electricity into cables for mains electricity in the national grid - why and how does it do this?

Answer 3

It increases the p.d, therefore decreasing the current! this reduces thermal energy transfer (to the surroundings), increasing the efficiency of power transmission

Question 4

Transformer Y is used to transform mains electricity in the national grid to peoples homes. why and how does it do this?

Answer 4

it decreases the potential difference to a safer value for homes

Question 5

difference between alpha external and internal radiation?

Answer 5

external - is stopped by skin and low penetrating so not very damaging!!!
internal - absorbed by living tissues, is highly ionising so the contamination can lead to cell mutation and possibly cancer

Question 6

what type of radiation do tracers use?

Answer 6

gamma

Question 7

what type of radiation does internal radiotherapy use

Answer 7

Beta

Question 8

what type of radiation does external radiation use?

Answer 8

high speed x rays

Question 9

what do control rods do?

Answer 9

absorb the neutrons and slow down the chain reaction

Question 10

4 cons of nuclear power stations

Answer 10

are very expensive to build, the waste is radioactive and is expensive to store, non renewable so will run out and there is a risk of a nuclear meltdown/explosion

Question 11

electromagnetic waves are what type of waves?

Answer 11

transverse

Question 12

sound waves are what type of waves?

Answer 12

longitudinal

Question 13

what does sound travel fastest through?

Answer 13

solids

Question 14

what does light travel fastest in (overall and a medium)

Answer 14

vacuum, and air

Question 15

what is most of the fusion occurring in stars?

Answer 15

Most of the fusion occurring in stars is hydrogen nuclei fusing to become helium nuclei

Question 16

why does fusion only happen at very high temperatures and pressures?

Answer 16

to overcome the repulsion of the positively charged nuclei

Question 17

Pros of gas power station vs coal

Answer 17

no sulphuric dioxide released, doesn’t cause acid rain, less carbon dioxide released, less global warming, gas mining is less destructive than coal mining

Question 18

in nuclear fission how many electrons are released?

Answer 18

2-3

Question 19

what radiation does nuclear fission release?

Answer 19

gamma rays

Question 20

in fusion what two lighter nuclei fuse to form what heavier nuclei

Answer 20

2 hydrogen goes to one helium

Question 21

why does the temperature in a kettle take a while to increase

Answer 21

as the heating element takes time to heat up

Question 22

if a question asks if two values are inversely proportional how can you explain it?

Answer 22

the two values multiplied by each other will be constant eg nv is 224, 316, etc

Question 23

at what speed do particles in a gas and liquid move

Answer 23

random speeds

Question 24

if there is a brick at the bottom of a pool, what forces are acting on it to make it stationary

Answer 24

upthrust acts upwards, while normal contact acts upwards and weight acts downwards and it is equal to the force exerted by two upwards forces leading to a resultant force of 0 and a stationary block!

Question 25

what is the relationship between the resistance and the length of a wire at a constant temperature

Answer 25

they are directly proportional to each other and so it is a straight line through the origin

Question 26

what happens when a spring is compressed and how does this help someone jump higher eg on a trampoline

Answer 26

elastic potential energy increases, which is then transferred to the gravitational potential energy store and as the total energy remains constant it allows the gymnast to jump higher

Question 27

why should an investigation with a spring be done on the floor but table

Answer 27

as it decreases any hazards : a spring on the table may jump and knock over items or spring into someone when mass is removed whereas it’ll be safer on ground

Question 28

how do you tell if the braking force has decreased

Answer 28

the train will decelerate at a slower rate

Question 29

what colour is a fuse and what’s the symbol?

Answer 29

brown - it’s a line through a rectangle

Question 30

At a height of 40km a rocket stops burning fuel but continued upward to a max height of 60km. Explain why velocity decreases between 40 and 60km? USE FRAV

Answer 30

as there is no fuel, the upwards force of thrust decreases, and the weight will also decrease due to the increase in height but not as drastically meaning the rocket decelerates and hence the velocity must decrease

Question 31

what is an electric field

Answer 31

a region around a charged object where another charged object experienced a force

Question 32

why does a trolley move faster and easier along a flat floor than a carpet

Answer 32

at there’s less friction between the floor and wheels, so therefore the resultant force increases and the trolley moves faster

Question 33

what is the relationship between distance from earthquake to seismometer and time between p and S waves arriving?

Answer 33

distance is directly proportional to the time between p and S waves arriving

Question 34

what is the control variable in the trolley investigation

Answer 34

mass of trolley + mass hanger

Question 35

how to get max velocity from mean velocity ?

Answer 35

multiply by 2

Question 36

one similarity of all electromagnetic waves

Answer 36

they are transverse and hence can travel through a vacuum

Question 37

what are 2 examples of precautions taken to reduce hazard caused by radioactive waste?

Answer 37

buy radioactive waste, store the waste in metal containers

Question 38

how to work out uncertainty

Answer 38

range/ 2

Question 39

why does the students hair stand up when they touch the electron ball?

Answer 39

electrons are transferred to the student her hair is negatively charged like charges repel, so therefore the electrons on hair repel each other leading to hair standing on end

Question 40

Determine p.d if thermistor when resistance at 20 degrees is 80 ohms, the V supplied to the circuit is 12V, and the resistance in circuit is 400 ohms

Answer 40

- first determine Overall resistance by adding 80 and 400 - 480 ohms - work out current from V= IR,substituting in 480 ohms and 12V - therefore current is 0.025A - work out p.d from V=IR - p.d = 2 ohms

Question 41

why do parachutes allow the passenger module to fall either a lower terminal velocity?

Answer 41

parachutes increase the effective area, so it slows down quicker, so the same air resistance at a lower speed, therefore a resultant force of 0 at a lower speed and hence a lower terminal velocity

Question 42

Steps of convection - As a fluid is ? the particles gain kinetic ? and spread further ?. - This causes the fluid to become ? dense and so it will rise ? any cooler fluid that ? been heated (because that fluid is more ?). - As the fluid cools down it will become more ? again, and so sink ? down. - If this process takes place in a ? space, like a container or a room, it can create a ? current.

Answer 42

- heated, energy, apart - less, above, hasn’t, dense - dense, back - limited/enclosed, convection

Question 43

Which type of heat loss do foam seals around windows and doors help to minimise

Answer 43

Heat loss by convection

Question 44

Which of the following are features of a house which help to reduce heat loss by conduction?

Answer 44

Double glazed windows Cavity walls Walls made of a material with low thermal conductivity

Question 45

What heat loss do single and double glazing reduce??

Answer 45

Convection

Question 46

Why do cars and plans have a streamlined shape

Answer 46

To reduce friction from air resistance and so they can use less fuel