Waves and optics

Question 1

Label the diagram of the wave: amplitude, peak, wavelength, peak, trough

Answer 1

Question 2

What does a wave transfer

Answer 2

Energy without transferring matter

Question 4

What is the wavelength of a wave

Answer 4

• The distance from a point on one wave to the same point on the next wave
• Usually measured from the peak of the wave

Question 5

What is the amplitude of a wave

Answer 5

• The height of the wave, measured from its middle to the top

Question 6

What is the frequency of a wave

Answer 6

• The number of waves passing a point every second

Question 7

What is the unit of frequency

Answer 7

hertz (Hz)

Question 8

How do the points vibrate in a transverse wave

Answer 8

The points along the wave vibrate at 90 degrees to the direction in which the wave is moving

Question 9

How do the points vibrate in a longitudinal wave

Answer 9

The points along the wave vibrate in the same direction that the wave is moving in

Question 10

example of longitudinal wave

Answer 10

sound waves

Question 11

Example of a transverse wave

Answer 11

light waves

Question 12

What is the equation for wave speed including wave speed, frequency and wavelength

Answer 12

• wave speed = Frequency x wave length
• v = f x l
• m/s = Hz x metres

Question 13

What happens when a wave reflects of a plane surface

Answer 13

Angle of incidence = angle of reflection

Question 14

How can a wave undergo refraction

Answer 14

• When a wave enters a different medium it changes speed, this is called refraction
• Refraction causes wavelength to increase or decrease
• And cause a change in direction

Question 15

What happens when water goes from shallow to deep water

Answer 15

The waves speed up

Question 16

What happens to the wavelength when waves speed up

Answer 16

The waves spread out

• When slowing down they bunch together

Question 17

What is diffraction of a wave

Answer 17

• When waves pass through a narrow gap, the waves spread out, this is called diffraction

Question 18

What happens to a wave with a small gap in diffraction

Answer 18

Question 19

What happens to a wave in a larger gap in diffraction

Answer 19

Question 20

What happens in diffraction around an edge

Answer 20

Question 21

When an object is placed in front of a mirror, what are its characteristics

Answer 21

• The image is the same size as the object
• The image is as far behind the mirror as the object is in front
• It is directly in line with the object

Question 22

Draw out an example of a virtual image in a mirror

Answer 22

Question 23

How is a virtual image formed

Answer 23

It is formed from the divergance of rays from the image

Question 24

What phrase describe the travel of light in refraction

Answer 24

1. Enters towards (the medium)
2. Leaves away (from the medium

Question 25

What is the critical angle

Answer 25

the angle of incidence beyond which rays of light passing through a denser medium to the surface of a less dense medium are no longer refracted but totally reflected.

Question 26

What is the equation for the refractive index involving angle of incidence, angle of reflection, refractive index

Answer 26

n = sin(i) / sin(r)

Question 27

What is the equation for a refractive index involved refractive index, speed of light in vacuum and speed of light in material

Answer 27

n = speed of light in vacuum / speed of light in material

Answer 28

n = 1/sinC

Question 29

When does internal reflection occur

Answer 29

when light moves from a denser medium to a less dense one

Question 30

Conditions for total internal reflection to occur

Answer 30

* Light is travelling from a more dense to less dense medium * The angle of incidence must be greater than the critical angle

Question 31

What is a real world use of internal reflection

Answer 31

Optical fibres in medicine and communications

Question 32

How do optical fibres work

Answer 32

Light travelling down the fibres is reflected each time it hits the wall of the fibre

Question 33

what are the steps to form a real image

Answer 33

1. Draw a line directly through the centre of the lens from the top of the object 2. Draw a line straight across from the top of the object 3. Once it reaches the centre line of the converging lens, it then travels towards the principal focus

Question 34

How does dispersion occur

Answer 34

* White light enters a denser medium * The colours which make up white light refract at different rates *

Question 35

Which colour in light has the longest and shortest wavelength

Answer 35

* Red has the largest * Violet has the shortest