Waves

Question 1

What do waves do

Answer 1

They transfer energy from one point to another via vibrations

Question 2

What way do particles in a longitudinal wave move

Answer 2

They move straight from left to right compressing and rarefacting

Question 3

What way do particles in a transverse wave move

Answer 3

Move up and down from left to right pulsing but going right back to the starting point

Question 4

Give 2 example of longitudinal waves and 2 examples of transverse waves

Answer 4

Sound and ultrasound are longitudinal

Water and electromagnetic are transverse

Question 5

What is the wave equation

Answer 5

V=f x wave length

Question 6

Define frequency of a wave

Answer 6

The number of complete waves passing a fixed point in one second

Measured in hertz (Hz)

Question 7

Define wavelength

Answer 7

Difference between 2 consecutive crests

Measured in meters (m)

Question 8

Define amplitude of a wave

Answer 8

The greatest displacement of the wave from its undisturbed position

Measured in metres(m)

Question 9

Describe how plane waves are reflected at plane barriers

Answer 9

The angle of I always = the angle of r

Wavelengths and frequencies of both waves are equal

There is continuity of incident and reflected waves at the barrier

Question 10

Describe how plane waves are refracted at plane boundaries

Answer 10

The angle of I in deep water Is always bigger than the angle of r in shallow water

Wavelength and speed of waves in deep water than waves in shallow water

Frequencies in deep and shallow water waves are the same

There is continuity of incident and refracted waves at the boundary

Question 11

What is the echo equation

Answer 11

S=2D/t

Question 12

What are the applications of echos

Answer 12

Scanning metal castings for faults or cracks eg rails

Scanning a pregnant woman’s womb to check on the development of the baby

Scanning soft tissues to diagnose cancer

Mapping the surface of the ocean floor

Question 13

Explain why a second echo may be detected

Answer 13

The ground is uneven so it took longer for the wave to reach the deeper part of the floor

Or 1 from object 1 from floor

Question 14

What’s the difference between the regions of the em spectrum

Answer 14

Radio lower frequency larger wavelength

Gamma rays higher frequency smaller wavelength

Question 15

What is the order of the em spectrum

Answer 15

Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays

Question 16

What is the visible spectrum

Answer 16

It is a small section of a complete spectrum

Question 17

What are the dangers of em waves

Answer 17

Gamma rays and x-rays - disrupts DNA which may lead to cancer

uv light - damages skin cells potentially leading to skin cancer

Visible light - can damage the eyes potentially causing snow blindness

Infrared light - felt as heat and can cause burns

Microwaves - cause internal heating of body tissues which, some say, can lead to cataracts

Radio waves - can cause cancer, leukaemia and other disorders