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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

What is the absolute refractive index of a material?

The ratio between the speed of light in a vacuum and the speed of light in that material.