Waves

Question 1

What is frequency?

Answer 1

The number of complete waves passing a certain point each second.

Question 2

What is meant by the term “period” in waves?

Answer 2

The amount of time it takes for a complete wave to pass a point.

Question 3

What is amplitude?

Answer 3

The maximum displacement of a point on a wave from its rest position.

Question 4

What is wavelength?

Answer 4

The length of a full cycle of a wave.

Question 5

What are the three types of transverse waves?

Answer 5

> ripples in water.
electromagnetic waves.
↳ e.g. light.
waves on a string.

Question 6

What are transverse waves?

Answer 6

Oscillations perpendicular (at 90°) to direction of energy transfer.

Question 7

What are longitudinal waves?

Answer 7

Oscillations parallel to direction of energy transfer.

Question 8

What is wave speed?

Answer 8

Speed at which a wave transfers energy or speed the wave moves at.

Question 9

What is the formulae for wave speed?

Answer 9

wave speed = frequency x wavelength
v = f x ℷ
m/s Hz m

Question 10

What is the process of measuring the speed of sound?

Answer 10

> speak attached to signal generator of specific frequency.
waves detected at each microphone shown as separate waves.
↳ move one microphone until waves line up.
↳ distance between microphones is now equal to one wavelength.
↳ use wave equation to find speed.

Question 11

What is refraction?

Answer 11

When a wave changes direction as it crosses a boundary between two materials at an angle to the normal.

Question 12

What happens when a wave refracts slows down?

Answer 12

The wavelength decreases and bends towards normal.

Question 13

What happens when the wave refracts speeds up?

Answer 13

The wavelength increases and bends away from normal.

Question 14

What is the electromagnetic (EM) spectrum?

Answer 14

radio waves ⟶ microwaves ⟶ infrared ⟶ visible light ⟶ ultraviolet ⟶ x-rays ⟶ gamma rays.

Question 15

What happens to the frequency, wavelength and colour as you go down the electromagnetic (EM) spectrum?

Answer 15

The frequency increases, the wavelength decreases and the colour goes from red to violet.

Question 16

What are some facts on EM waves?

Answer 16

> they are transverse.
transfer energy from source to absorber.
travel at same speed in air or vacuum.

Question 17

How are radio waves produced?

Answer 17

> alternating current supplied which is shown on an oscilloscope.
↳ electrons oscillate producing radio waves in the transmitter.
↳ emitted radio waves transfer energy.
↳ radio waves absorbed causing electrons in receiver to oscillate
in the receiver.
↳ alternating current of same frequency as radio waves
induces in receiver.

Question 18

What are the uses of radio waves?

Answer 18

> TV.

> radio.

Question 19

What are the uses of microwaves?

Answer 19

> satellite communications.

> cooking.

Question 20

What are the uses of infrared radiation?

Answer 20

> electric heaters.
cooking.
infrared cameras.

Question 21

What are the uses of visible light?

Answer 21

Communications through optical fibres.

Question 22

What are the uses of UV waves?

Answer 22

> energy efficient lights.

> sun tan beds.

Question 23

What are the uses of x-rays and gamma rays?

Answer 23

> medial imaging.

> medical treatments.

Question 24

What is a radiation dose?

Answer 24

The measure of the risk of harm to body tissues due to exposure to radiation.
[measured in sieverts]

Question 25

What are the harmful effects of UV radiation on human body tissue?

Answer 25

> can prematurely age skin.

> increase risk of skin cancer.

Question 26

What are the harmful effects of x-ray and gamma rays on human body tissue?

Answer 26

> gene mutation.

> cancer.

Question 27

What are the two types of waves?

Answer 27

> transverse.

> longitudinal.

Question 28

What are sound waves travelling through air?

Answer 28

Longitudinal.