Flashcards in 4.4 Waves Deck (57)

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1

## How can you tell electromagnetic waves carry energy?

###
-things heat up

-ionisation

-loud sounds cause large oscillations in air partials which can make things vibrate

-wave power can be used to generate electricity

2

## Define displacement.

### How far a point on the wave has moved from its undisturbed - it can be positive or negative.

3

## Define amplitude.

### Amplitude is the maximum displacement - the distance from a peak to trough to the mean (rest) position.

4

## Define wavelength.

### The distance between two successive identical points that have the same pattern of oscillation. The distance a wave travels before it repeats itself.

5

## Define period.

### The time it takes for one complete cycle of oscillation go take place at any point.

6

## Define phase difference.

### Measured in radians. The amount one wave lags behind the other -the relationship between the pattern of vibration at two points.

7

## Define frequency.

### The number of oscillations per second passing a given point.

8

## Equation for frequency.

### Frequency = 1/Time

9

## Equation for speed of wave (v).

### Speed of wave (v) = frequency (f) x wavelength (y)

10

## What is intensity?

### A measure of how much energy a wave is carrying

11

## Define progressive wave.

### A type of wave that travels through a substance or space, carrying energy via the oscillation of particles

12

## Define transverse wave.

### A type of wave in which oscillations occur at right angles to the direction of wave propagation.

13

## Define longitudinal wave.

### A type of wave in which oscillations occur parallel to the direct of wave propagation.

14

## Define coherence.

### Constant phase difference.

15

## Why is it difficult to produce coherent light waves?

### It is difficult to control the frequency.

16

## Equation for fringe spacing?

### X=(wavelength x D)/ a (spacing between slits)

17

## What is the equation for intensity?

### Power/area

18

## What's intensity measured in?

### Wm^-2

19

## What do all electromagnetic waves have in common?

###
-speed

-transverse

-can be refracted, reflected, diffracted and can undergo interference

-their progressive waves carry energy

-can be polarised

20

## Wavelength of radio waves.

### 10^-1 to 10^6

21

## Wavelength of microwaves.

### 10^-3 to 10^-1

22

## Wavelength of infrared waves.

### 7x10^-7 to 10^-3

23

## Wavelength of visible light.

### 4x10^-7 to 7x10^-7

24

## Wavelength of UV waves.

### 10^-8 to 4x10^-7

25

## Wavelength of X-rays

### 10^-13 to 10^-8

26

## Wavelength of gamma rays.

### 10^-16 to 10^-10

27

## What happens if the second polarising filter is rotated by 45 degrees?

### The intensity will be half that getting through the first filter.

28

## When do you get the most diffraction?

### When the gap is the same size as the wavelength.

29

## What does refractive index measure?

### How much a material slows down light.

30