Flashcards in Physics definitions Deck (39):

1

## photon

###
-a very small quanta of discrete light energy

- can be an electromagnetic wave or particle

2

## Absorption spectrum

### - a coloured background with black lines

3

## Emission spectrum

### a black background with coloured lines

4

## a moment

###
the perpendicular distance to the pivot times the force

- forces up equal forces down

- anticlockwise moments equal clockwise moments

5

## Equilibrium

### an object is in equilibrium when the resultant forces acting on a particle is zero

6

## Couples

### a pair of forces equal in magnitude and opposite in direction

7

## Centre of mass

### the point at which your mass acts through

8

## Difference between centre of mass and centre of gravity

### the gravitational field is not uniform

9

## How to improve centre of mass

###
lower centre of mass

widen base of the object

10

## kinetic energy

### energy associated with anything that is moving

11

## elastic collisions

###
kinetic energy and momentum is conserved

small scale

12

## inelastic collisions

###
momentum is conserved

large scale

13

## Impulse

### the rate of change of momentum

14

## current

### the flow of charge per unit time

15

## voltage

### how many joules of work each coulomb of charge is capable of doing

16

## potential difference

###
-the energy transfer per unit/ from electrical to other

-charge losing energy

17

## Electromotive force

### the charge gaining energy

18

## resistivity

### the resistance a metal puts up to electric current

19

## hooke's law

### the force exerted on a spring is proportional to its compression, such that force divided by compression is equal to a constant k, which is measured in Nm

20

## thermistor

### a device that decreases its resistance as temperature increases

21

## Young modulus

### the modulus of elasticity

22

## Brittle

### something which shatters if a large stress is applied

23

## Ductile

### a material that can be easily shaped under tension

24

## Malleable

### a material that can be easily shaped under compression

25

## Wavelength

### the distance between two identical points on successive waves

26

## amplitude

### the maximum displacement of a wave

27

## period

### the time taken for one complete wave to pass a point

28

## frequency

### the number of waves that passes a fixed point per unit time

29

## transverse waves

### waves that have their displacement at 90 degrees to the direction of energy transfer

30

## longitudinal waves

### waves that have their displacement in the same direction as the energy transfer

31

## phase difference

### the amount a wave is in or out of sequence with another wave

32

## Coherence

### when two waves have a constant phase difference

33

## refraction

### when a wave travels from a fast medium to a slow medium or vice versa causing waves to slow down and speed up and turn

34

## Interference

### when two waves meet at a point, the resultant displacements the sum of individual displacements

35

## path difference

###
-if the path difference is even and whole waves, the waves will arrive in phase

- if odd the waves will arrive out of phase

36

## superconductivity

###
zero resistance

- occurs at low temperature

- has no resistance after a certain critical temperature

37

## antiparticle

###
different charge

same mass, rest mass energy

38

## hadrons

###
heavier

not fundamental

made of fundamental quarks

interacts with SNF,WNF and electrostatic if charged

39