Waves

Question 1

Complete this sentence .
Waves transfer ____ and ____
without transferring _______.

Answer 1

Waves transfer energy and information
without transferring matter.

Question 2

Define frequency and give its units

Answer 2

● The number of waves passing through a point per second.
● Hz (hertz)

Question 3

Define wavelength

Answer 3

The distance between two adjacent peaks on a wave.

Question 3

Define amplitude

Answer 3

● The maximum displacement of the wave from its equilibrium position.
● The distance between the centre of the wave and a peak

Question 4

What is meant by the period of the wave?

Answer 4

The length of time it takes for one full wave to pass through a point

Question 5

How can you calculate the wave speed?

Answer 5

● Wave speed (measured in metres per second) is equal to the product of the wavelength and the frequency of the wave.
● Wave velocity= f ×λ

Question 6

State an equation linking frequency and
period of a wave

Answer 6

Question 7

What is a longitudinal wave? Give some examples.

Answer 7

● Vibrations are parallel to the direction of energy transfer(wave)
● Examples include sound waves and earthquakes (seismic waves)

Question 8

What is a transverse wave? Give some example

Answer 8

● A wave with oscillations that are perpendicular ( 90 degrees) to the direction of energy transfer.
● Examples include electromagnetic waves

Question 9

Explain what is meant by “the doppler effect”

Answer 9

Question 10

At what speed does an electromagnetic wave travel in a vacuum?

Answer 10

Question 11

What types of waves are electromagnetic waves?

Answer 11

Transverse

Question 12

What do electromagnetic waves
transfer?

Answer 12

Energy and Information

Question 13

What are the four common properties of all
electromagnetic waves?

Answer 13

· They are all transverse waves
· They all transfer energy or information
· They all travel at the speed of light in vacuum
· They all can be reflected, refracted or diffracted

Question 14

Which part of the electromagnetic spectrum has the longest wavelength?

Answer 14

Radio waves

Question 15

Order the electromagnetic spectrum from the highest frequency to the lowest frequency.

Answer 15

1. Gamma Rays
2. X-Rays
3. Ultraviolet
4. Visible Light
5. Infrared
6. Microwaves
7. Radio Waves

Question 16

What are the colours of the visible light spectrum?

Answer 16

Red, Orange, Yellow, Green, Blue, and Violet.

Question 17

a.Which colour has the highest frequency?
b.Which colour has the lowest frequency?
c.Which colour has the lowest wavelength?
d.Which colour has the highest wavelength?

Answer 17

a.Which colour has the highest frequency? Violet
b.Which colour has the lowest frequency? Red
c.Which colour has the lowest wavelength? Violet
d.Which colour has the highest wavelength? Red

Question 18

What are the uses of radio waves?

Answer 18

● For communication through radio
● Used for satellite transmissions

Question 19

What are microwaves used for?

Answer 19

● Cooking in microwaves ovens
● Communications
● Satellites

Question 20

Which part of the electromagnetic spectrum is used in cooking, thermal imaging and television remote controls?

Answer 20

Infrared

Question 21

Give examples of uses for visible light?

Answer 21

● Allows us to see (used for vision)
● Photography
● Optical Fibres (endoscope,communication)

Question 22

What part of the electromagnetic spectrum is used to for security marking and in fluorescent lamps?

Answer 22

Ultraviolet

Question 23

What are some uses of x-rays?

Answer 23

● Scanners at airports
● Medical x-ray machines

Question 24

What are the uses and disadvantages of gamma rays?

Answer 24

● Used to sterilise food and medical equipment ● Used in cancer diagnosis **But** Can cause mutations or damage to body cells. This could lead to death.

Question 25

What are the disadvantages of microwaves?

Answer 25

They can cause heating of internal tissues in the body

Question 26

Which part of the electromagnetic spectrum is used in TV remotes and can also cause skin burns?

Answer 26

Infrared

Question 27

Does the danger that is associated with electromagnetic waves increase with frequency or with wavelength?

Answer 27

With frequency

Question 28

What are the dangers of excessive exposure to ultraviolet?

Answer 28

You could damage your eyes and the cells on the surface of your skin. This could lead to skin cancer or eye conditions.

Question 29

What is the normal (in terms of reflection and refraction)?

Answer 29

A vertical imaginary line which is perpendicular to the boundary.

Question 30

What happens when light is reflected off a boundary?

Answer 30

It is reflected (bounces) off a smooth flat surface so that the angle of incidence (the angle it comes in at) is the same as the angle of reflection (the angle it leaves at).

Question 31

What happens when light is refracted while passing through 2 different media?

Answer 31

● The light changes speed and direction in the new medium ● If the new medium is more dense, the light will travel slower and bend towards the normal ● If the new medium is less dense, the light will travel faster and bend away from the normal

Question 32

State an equation linking angle of incidence, angle of refraction and refractive index

Answer 32

Question 33

What is the critical angle?

Answer 33

The angle of incidence which causes the angle ofreflection to be 90 degrees so that that the light refracts onto the boundary.

Question 34

State an equation linking critical angle and refractive index

Answer 34

Question 35

What is total internal reflection?

Answer 35

When light is trying to pass from a less dense medium to a denser medium, it can be reflected back to the less dense medium if the angle of incidence is larger than the critical angle between two media. This reflection is called Total Internal Reflection.

Question 36

State two uses of total internal reflection

Answer 36

- Endoscopes - Periscopes - Optical Fibres - Cat Eye Reflectors - Shining of Diamonds

Question 37

If light hits a boundary at 90 degrees to the surface, will the light refract?

Answer 37

No it will not