Physics general

Question 1

difference between compression & rarefaction

Answer 1

compression = region of high pressure / where particles are close together

rarefaction = region of low pressure / where particles are further apart

Question 2

how does turning the coil induce voltage+

Answer 2

coil cuts magnetic field lines / coil experiences changing magnetic field

Question 3

formula between energy and heat capacity

Answer 3

energy = mass x capacity x change in temp

unit : J

Question 4

conduction in solid

Answer 4

thermal energy transferred as energy of atoms // particles vibrate more // vibration passed through metal

Question 5

why a rotating coil generator produces an alternating current

Answer 5

coil cuts lines of magnetic field // e.m.f induced // each side of coil moves upwards and then downwards // current changes direction every half turn

Question 6

effect of increasing freq on the time taken for pulse to travel and return

Answer 6

time remains the same bc wave velocity doesn’t change

Question 7

differences between longitudinal and transverse waves

Answer 7

longitudinal : direction of propagation parallel to direction of oscillation
transverse : direction of propagation perpendicular to direction of oscillation

Question 8

how does slip rings produce an alternating voltage output from the rotating coil

Answer 8

induced voltage changes every half turn // same side of coil remains connected to same slip ring

Question 9

why expansion occurs when atoms are heated

Answer 9

atoms have greater vibration // about a fixed point so take up more space - average distance between particles increases

Question 10

differences between evaporation and boiling

Answer 10

E : at any temp, B : only at boiling point
E : happens at the surface, B : throughout the liquid
E : can occur using the internal energy of the system, B : source of heat
E : produces cooling, B : does not produce cooling
E : slow process, B : rapid process

Question 11

electromotive force definition

Answer 11

energy/work done per unit charge

Question 12

why parallel circuit

Answer 12

if one lamp fails the other will still work // still a complete circuit

Question 13

why does ray lof light stay inside the optical fibre

Answer 13

angle of incidence greater than critical angle // total internal reflection

Question 14

how does wider tyres reduce the pressure

Answer 14

larger surface area // p = f / a

Question 15

difference between magnetic properties of iron and steel

Answer 15

iron magnetises quicker , steel magnetises slower

Question 16

dexcribe the structure of a thermocouple

Answer 16

two different metals // joined together

Question 17

virtual image vs. real image

Answer 17

R : formed where light rays converge
V : formed from where light rays appear to have diverged from

R : can be formed on a screen
V : cannot be formed on a screen

Question 18

difference between alternating current and direct current

Answer 18

in DC, electric charge only flows in one direction
in AC, electric chrage changes direction

Question 19

energy transformation that occurs in the generator

Answer 19

kinetic to electrical // electrical to light

Question 20

use for think converging lens

Answer 20

magnifying glasses

Question 21

define equilibrium

Answer 21

no resultant force AND no resultant turning effect

Question 22

method of determining the volume of an irregular object

Answer 22

immerse in water // measure volume of displaced water

Question 23

what causes tides

Answer 23

moon

Question 24

how transformer produces a reading on a voltmeter

Answer 24

alternating potential difference applied to p coil
alternating current flows in the p coil
producews a changing magnetic field in the p coil
s coil experiences a changing magnetic field
produces an alternating potential difference across the voltmeter

Question 25

what causes refraction

Answer 25

change of speed at the boundary between materials

Question 26

define e.m.f

Answer 26

energy supplied by a source in driving charge around a complete circuit

Question 27

functions of slig-ring

Answer 27

prevent wires tangling // maintain electrical contact

Question 28

how thermal energy is transferred through the glass of thermometer

Answer 28

conduction / vibrations passed from particle to particle

Question 29

adv and disadv of using coal to generate electricity

Answer 29

reliable // easily combustible // abundant // easily available

releases CO2 // causes global warming // climate change // non-renewable resource

Question 30

why high potential difference

Answer 30

reduces current // reduces power losses

Question 31

what is meant by transverse waves

Answer 31

transfers energy through vibrations
oscillations are perpendicular to direction of energy transfer

Question 32

what happens to readings on the ammeter and voltmeter when the temp of thermistor increases

Answer 32

ammeter - increases
voltmeter - decreases

Question 33

hooke’s law

Answer 33

extension is directly proportional to the force applied

Question 34

why steam is able to fill the container

Answer 34

particle movement is random ;
rapid movement of particles / high kinetic energy of particles ;
particles are far apart
forces between molecules are, weak / zero ;

Question 35

why total internal reflection occurs

Answer 35

angle of incidence exceeds critical angle;

Question 36

why alpha source is used to treat cancer cells

Answer 36

kill cells / it is ionising

Question 37

define electric field

Answer 37

region in which an electric charge experiences a force

Question 38

why use fixed resistor

Answer 38

reduces potential difference across wire
stop wire melting
reduce current through the wirev