Topic 5 Light And The Electromagnetic Spectrum(completed)

Question 1

What is the difference between specular and diffuse reflection

Answer 1

Specular - light reflects off of a smooth surface
Diffuse-light reflects off of a not smooth surface

Question 2

Explain a filter of red light works

Answer 2

Shine white light through red filter
Red filter absorbs all white light except red
Red light transmits and red light is show

Question 3

Explain how we see a red apple when white light is shone into it

Answer 3

White light shone into apple
Apple absorbs all white light except colour red
Red wave reflects off to our eye and we see apple as red

Question 4

Explain how see black when a green light filter is shone on a red apple

Answer 4

Green light filter only transmits green light
Red apple can only reflect of red light
Green wave is absorbed and our light detects it as black

Question 5

Angle of incidence = Angle of reflection

Question 6

What is the angle of incident

Answer 6

The angle between the incident ray(incoming ray) and between the normal(perpendicular to where the light hits the boundary)

Question 7

What is the angle of reflection

Answer 7

The angle between the normal (perpendicular to where the light ray hits the boundary) and the reflected ray

Question 8

What is total internal reflection

Answer 8

When all of the light that hits a boundary is reflected back

Question 9

What is the critical angle

Answer 9

The angle at which light hits and some rays go along the surface the light hits and some is reflected

Question 10

What does a diverging lense do to light

Answer 10

Spreads light out more

Question 11

What does a converging lense do to light

Answer 11

Causes light to be brought together closer(converge)

Question 12

What is the focal length

Answer 12

The distance between the middle of the lense to the focal point where light meets or is supposed to meet

Question 13

Real image
Light rays come together on a screen
Light rays form where image seems to be

Question 14

Virtual image
Light rays from object appear to be coming from different place to where they actually are
Light rays don’t come to point so can’t be captured on screen(eg magnifying glass makes object look bigger than it actually is)

Question 15

All electromagnetic waves are _____ waves

Answer 15

Transverse waves
Travel at same speed in vaccum

Question 16

What is the order of the electromagnetic waves

Answer 16

Radio waves-microwaves-infrared-visible light-UV-X-rays-gamma rays

Question 17

What is the order of colours of visible light

Answer 17

Red orange yellow green blue indigo violet

Question 18

How does the power of a lense relate to its focal length and shape

Answer 18

More powerful means the shorter focal length and more curved it is

Question 19

In electromagnetic waves the wavelength ______ and the frequency ______

Answer 19

Decreases
Increases

Question 20

Different substance can make waves act differently when the waves hit the surfaces of them depending on wavelength

Question 21

All objects are always emitting and absorbing radiation ,what do the wavelengths and the intensity of the waves depend on

Answer 21

The temperature of the object

Question 22

Waves with higher frequencies have higher potential danger

Question 23

Give one harmful effect of too much exposure to each
Microwaves
Infrared
UV
X ray/Gamma

Answer 23

Microwave-internal heating of body cells
Infrared-skin burns
UV-damage to skin cells leading to cancer
X rays/gamma-mutation or damage to cells

Question 24

Give worldly uses of each of these
Radio waves
Microwaves
Infrared
Visible light
UV
X ray
Gamma

Answer 24

Radio waves-broadcasting and communication
Microwaves-communication,heating food
Infrared-thermal imaging,short range communications
Visible light-vision ,photography
UV-fluorescent lamps,disinfecting water
X rays-seeing internal structure of objects,medical x rays
Gamma rays-disinfecting food and medical equipment

Question 25

Radio waves can be produced by oscillations in electrical circuits

Question 26

EM waves are generated by a variety of changes in atoms giving off large ranges of frequencies
EG
Changes in nucleus
Changes in electron shells

Question 27

State one way of reducing risk to doctor who uses gamma radiation

Answer 27

Use for limiter time
Distance yourself from the gamma

Question 28

State 2 sections of the electromagnetic spectrum used for communications

Answer 28

Radio waves
Microwaves
Infrared (short range communications)

Question 29

State 2 differences between ultrasound and ultraviolet waves

Answer 29

1
Us longitudinal
UV transverse
2
US needs medium
3
UV EM wave

Question 30

What happens to a body if he average power it emits is more than it absorbs

Answer 30

The temperature will decrease

Question 31

For a body to stay at a constant temperature it must emote and absorb same amount of ______

Answer 31

Radiation/power
If it absorbs more the temp will increase
If it emits more the temperature will decrease

Question 32

What causes earth to absorb more power/radiation than it is emitting

Answer 32

The greenhouse gases in the atmosphere prevent heat from escaping back into space so temperature is increasing(global warming)