P1c: A spectrum of waves

Question 1

Describe the main features of a transverse wave(5)

Answer 1

Trough - lowest point on a wave below its rest position

Crest - highest point on a wave below its rest position

Amplitude - maximum displacement of a wave measured from the rest position (middle)

Wavelength - distance between two consecutive crests/troughs(measured in metre(m))

Frequency - number of complete waves passing a point in one second(measured in hertz(Hz))

Question 2

Wave speed equation

Answer 2

wave speed(m/s) = frequency × wavelength

Question 3

Why does refraction occur at the boundary between mediums

Answer 3

the wave changes in speed and direction when it passes from one medium to another(frequency stays the same but the wavelength changes)

Question 4

What is diffraction

Answer 4

The spreading out of a wave as it passes through a gap or around an obstabcle

Question 5

What happens when a wave enters a more dense medium(2)

Answer 5

Speed decreases, refracted line bends towards normal

Question 6

What happens when a wave enters a less dense medium(2)

Answer 6

Speed increases, refracted line bends away from normal

Question 7

What affects how much diffraction takes place? (3)

Answer 7

the size of the gap relative to the wavelength of the wave

• the longer the wavelength/small the gap, the greater the diffraction
• strongest diffraction occurs when the gap is the same size as the wavelength

Question 8

What are diffraction effects noticeable in(2)

Answer 8

telescopes

optic microscopes

Question 9

What are the limiting effects of diffraction on wave based sensors (optical microscope or telescope) (2)

Answer 9

when light enters the instrument, it passes through a small gap and diffracts a little
-this can lead to a blurry image or a loss of detail

Question 10

List the 7 types of electromagnetic waves(highest wavelength - lowest wavelength/lowest frequency - highest frequency)

Answer 10

Radio waves

Microwaves

Infrared

Visible light

Ultraviolet

X-ray

Gamma ray

Question 11

What does the size of a communication receiver depend on

Answer 11

The wavelength of the radiation

(-so the communication receiver is larger for radio waves than microwaves)