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!