3.1-3.23

Question 1

Transverse Wave

Answer 1

Wave vibrates (oscilates) at right angles to the direction it is travelling

Question 2

Longitudinal Wave

Answer 2

Wave vibrates (oscilates) are along the same direction as the energy wave is moving

Question 3

Wavefront

Answer 3

Created by overlapping lots of different waves. A wavefront is where all the vibrations are in phase and the same distance from the source

Question 4

Amplitude

Answer 4

The distance from their equilibrium position to the peak

Question 5

Wavelength

Answer 5

The distance between a particular point on one cycle of the wave and the same point on the next cycle

Question 6

Waves are…

Answer 6

a way of transferring energy from place to place, energy is transfered but matter is not.

Question 7

Frequency

Answer 7

The number of waves passing a particular point per second. Is measured in Hertz (Hz)

Question 8

Time period

Answer 8

The time it takes for one complete wave to pass a particular point

Question 9

wave speed equation

Answer 9

wave speed = freguency x wavelength

v = f × λ

Question 10

frequency equation

Answer 10

frequency = 1 / time period

Question 11

Doppler effect

Answer 11

An increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other.

Question 12

Waves can…

Answer 12

Be reflected and refracted

Question 13

Electromagnetic spectrum

Answer 13

A continuos spectrum of waves, which includes visible light

radio, microwave, infrared, visible, ultraviolet, x-ray and gamma ray radiations
-All these waves travel at the same speed in free space

Question 14

Visible light order

Answer 14

Red, orange, yellow, green, blue, indigo, violet

Question 15

uses of electromagnetic radiations:

Answer 15

radio waves: broadcasting and communications
• microwaves: cooking and satellite transmissions
• infrared: heaters and night vision equipment
• visible light: optical fibres and photography
• ultraviolet: fluorescent lamps
• x-rays: observing the internal structure of objects and materials, including for medical applications
• gamma rays: sterilising food and medical equipment.

Question 16

detrimental effects of excessive exposure of the human body to electromagnetic waves:

Answer 16

• microwaves: internal heating of body tissue
• infrared: skin burns
• ultraviolet: damage to surface cells and blindness
• gamma rays: cancer, mutation

Question 17

describe simple protective measures against the risks

Answer 17

wear sun glasses, sun cream and stay in shade for UV

Wear led clothing for Gamma

Question 18

Light waves…

Answer 18

are transverse waves and that they can be reflected and refracted

Question 19

Law of reflection

Answer 19

the angle of incidence equals the angle of reflection

Question 20

Refractive indesx (Snells Law):

Answer 20

n= sin i/ sin r

Question 21

Total internal reflection is used for…

Answer 21

transmit signals along optical fibres

Question 22

Critical angle is…

Answer 22

when light passes along the boundary

Question 23

Critical angle equation

Answer 23

sin C = 1 / n

Question 24

sound waves are…

Answer 24

longitudinal waves which can be reflected and refracted

Question 25

practical: investigate the refraction of light, using rectangular blocks, semi-circular blocks and triangular prisms

Answer 25

1. Set up your apparatus as shown in the diagram using a rectangular block.
2. Shine the light ray through the glass block
3. Use crosses to mark the path of the ray.
4. Join up crosses with a ruler
5. Draw on a normal where the ray enters the glass block
6. Measure the angle of incidence and the angle of refraction and add these to your results table
7. Comment on how the speed of the light has changed as the light moves between the mediums.
8. Repeat this for different angles of incidence and different glass prisms.

Question 26

practical: investigate the refractive index of glass, using a glass block

Answer 26

1. Set up your apparatus as shown in the diagram using a rectangular block.
2. Shine the light ray through the glass block
3. Use crosses to mark the path of the ray.
4. Join up crosses with a ruler
5. Draw on a normal where the ray enters the glass block
6. Measure the angle of incidence and the angle of refraction and add these to your results table
7. Calculate the refractive
   index
8. Repeat steps 2 – 7 using
   a different angle of
   incidence
9. Find an average of your
   results.