Light

Question 0

Draw a reflection diagram

Answer 0

Draw a periscope diagram

Question 1

Reflection is ..

Answer 1

• upright
• a virtual image
• laterally inverted
• the same size
• equal distance (equal distance inversion) behind the mirror as the object is in front

Question 2

I =

R =

Answer 2

Angle of incidence

Angle if reflection

Question 3

Always draw the … 90 degrees to the mirror

Answer 3

Normal (dotted line)

Question 4

Angle of incidence =

Answer 4

Angle of reflection

Question 5

Waves …

Answer 5

Transfer energy but not matter

Question 6

Peak of a wave

Answer 6

Point on a wave with the highest displacement. Adjacent peaks are separated by one wavelength.

Question 7

Trough of wave

Answer 7

Point on a wave with the lowest displacement. Adjacent troughs are separated by one wavelength.

Question 8

Amplitude of wave

Answer 8

Maximum displacement above or below the undisturbed position

Question 9

Wavelength

Answer 9

The distance from peak to adjacent peak or trough to adjacent trough

Question 10

Transverse wave

Answer 10

Vibrations are perpendicular to the direction of energy transfer

Question 11

Longitudinal wave

Answer 11

Vibrations are parallel to the direction of energy transfer

Question 12

Frequency

Answer 12

The number of vibrations per second. Measured in Hertz (Hz)

Question 13

Time period (t)

Answer 13

The time for 1 wave to be produced. Measured in second (s)

Frequency = 1/time period

Question 14

Diffraction

Answer 14

The spreading out of a wave
Waves with longer wavelengths diffract more
The amount of diffraction that occurs when a wave moves through a gap depends on the relative sizes of the gap and the wavelength
If the gap and wavelength are about the same size, there is a large amount of diffraction

Question 15

Refraction

Answer 15

The bending of light when travelling from one medium into another. Refraction occurs because light changes speed when it changes medium.

Question 16

When light slows down after hitting a medium

Answer 16

It bends (refracts) towards the normal and vice versa

Question 17

Snell’s law equation

Answer 17

Sin i / Sin r = n (refractive index)
n = speed of light / speed of light in glass
n = 3.00 x 10 (pw8) / 2.00 x 10 (pw8)
n = 1.5

Question 18

Refractive index of water

Answer 18

1.33

Question 19

Speed of light in air

Answer 19

3.0 x 10(8)m/s

Question 20

How yo calculate the refractive index of the glass prism

Answer 20

Measure the angle of incidence when the angle of refraction is 90 degrees, the i is the critical angle
Then use SinC = 1/n to calculate the refractive index

Question 21

When travelling from glass to air the light … And bends away from the normal

Answer 21

Speeds up

Question 22

Fibre optic cables

Answer 22

This is a cable made up of super-thin filaments of glass or other transparent materials that can carry beams of light therefore data can be transmitted at the speed of light

Question 24

Advantages of fibre optic cables over copper cables

Answer 24

Carry more information
No electro-magnetic interference
Unable to hack conversations

Question 25

describe what happens when a light is shone at a certain angle in a prism

Answer 25

• the em spectrum is formed in and through the other side of the prism
• blue comes at the bottom as it has a smaller wavelength
• red comes at the top as it has a greater wavelength
• EM spectrum forms in the middle of the blue and red
• both colours speed up when they leave the prism to the same speed
• blue has a greater refractive index and slows down more and refracts more in the prism
• red has a smaller refractive index than blue light and is faster in the prism than blue light therefore refracts less

Question 26

describes what happens in a periscope prism

Answer 26

total internal reflection is happening. no mirrors are used. the angle of the prisms have to be larger than the critical angle of 42 degrees otherwise a distorted image would be seen at the receiving end of the periscope

Question 27

why aren’t mirrors used in a pericope prism

Answer 27

as metal and glass will age over time and decrease in quality. this method can never age.