light and the electromagnetic spectrum

Question 1

what is the law of reflection?

Answer 1

the angle of incidence is equal to the angle of reflection.

Question 2

what is to total internal reflection?

Answer 2

when light is reflected completely inside the glass block.

Question 3

explain how total internal reflection is occurred.

Answer 3

when light passes from glass or water into air with small angles, most of the light is refracted and a very little light is reflected, but when the angle increases the angle of reflection also increases, and if you increase the angle of incidence even more the llight will be reflected completely inside the glass.

Question 4

describe what happens to the light ray when it goes from water into air?

Answer 4

when the light rays go from water into the air, its going from a dense medium into a less dense medium so the light rays will bend away from the normal, as its speed increases.

Question 5

what is diffuse reflection?

Answer 5

when light is reflected on a rough surfaces and it scatters in all directions.

Question 6

what is specular reflection?

Answer 6

when light is reflected on a smooth surface like a mirror and all the lights scatters evenly.

Question 7

what is ‘white light’?

Answer 7

white light is the light coming from the sun or the bulb, white light is a mixture of different colours of light that our eyes see as white. white light can split up into different colours of the visible spectrum with a glass prism.

Question 8

Explain why a yellow object looks yellow?

Answer 8

the object looks yellow because it absorbs every colour from the white light but reflects only yellow.

Question 9

what does the power of a lens describe?

Answer 9

describes how much it bends light that passes through it.

Question 10

what is a converging lens?

Answer 10

converging lens are lens that is fatter in the middle and thinner at the edges and when light passes through it,, the parallel rays of light converge (come together)

Question 11

what is a diverging lens?

Answer 11

diverging lens are lens that is thinner in the middle and fatter at the edges, when parallel rays of light passes through it, the rays of light diverges (come apart)

Question 12

what is a focal length?

Answer 12

focal length is the length from the focal point to the center of the lens.

Question 13

we see visible light as a range of colours from red to green to violet. Explain whether red or violet light has the higher frequency.

Answer 13

violet has the higher frequency, because lower frequencies appear to be more red, so therefore violet has a higher frequency.

Question 14

state two ways in which electromagnetic waves differ from one another.

Answer 14

they have different wavelength and they have different frequency.

Question 15

state two characteristics that all electromagnetic have in common.

Answer 15

they all travel at a same speed in a vacuum (3x10^8 m/s).

they all are transverse waves

Question 16

lower frequencies of visible light appears to be more____?

Answer 16

red

Question 17

higher frequencies of light appears to be more_____?

Answer 17

blue

Question 18

electromagnetic waves that have higher frequencies then visible light is called?

Answer 18

ultraviolet

Question 19

electromagnetic waves that have lower frequencies than visible light is called?

Answer 19

infrared waves

Question 20

what is the full range of electromagnetic waves called??

Answer 20

electromagnetic spectrum

Question 21

which transfers more energy, ultraviolet or visible light?a

Answer 21

ultraviolet transfers more energy then visible light.

Question 22

some materials absorb visible light and reemits it as visible light, what are these callled?

Answer 22

this is called flourescence.

Question 23

flourescent materials is only visible when u shine what on them?

Answer 23

it will be visible when u shine ultraviolet light on them.

Question 24

uses of x-rays

Answer 24

uses to for body scanning as it can pass or penetrate the skin and muscles.
as well as security scans like in the airport for luggages

Question 25

do bones absorb X-rays?

Answer 25

yes, some of it

Question 26

what are the uses of gamma rays?

Answer 26

gamma rays transfer a lot of energy so therefore they are used to sterilise food as well as medical equipments and kill very harmful micro-organisms.

Question 27

what is radiotherapy?

Answer 27

is a cancer treatment where they uses high doses of radiation to kill the cancer cells.

Question 28

uses of ultraviolet radiation

Answer 28

to make disinfect water as it can kill micro-organisms

Question 29

why heating with microwave could be dangerous to people?

Answer 29

it is because our bodies are mostly made up of water and so the microwaves could heat the cells from the inside.

Question 30

even though mobile phone signals uses microwaves, why is it proven that its not harmful?

Answer 30

because mobile phone signals uses microwaves with different frequency which wont harm us much.

Question 31

what are infrared radiations used for?/

Answer 31

toasters and grills to cook food

Question 32

what happens if we stand too near to a bonfire?

Answer 32

bonfire emits infrared radiations and if there is a lot of infrared radiations being emitted and we stand too close to it, it can destroy our body cells causing burns to the skin

Question 33

higher frequency waves transfers more energy than lower frequency waves, true or false?

Answer 33

true

Question 34

which is more dangerous, higher frequency waves or lower frequency waves and why?

Answer 34

higher frequency waves is more dangerous because it transfers more energy than lower frequency waves

Question 35

what happens if the ultraviolet radiation is transferred to our skin?

Answer 35

it can damage our skin and changes the DNA, and if we are exposed to a huge amount of ultraviolet radiation, it can cause skin cancer.

Question 36

how do we protect ourselves from these harmful effects of ultraviolet radiation? (sun light)

Answer 36

stay away when there is a heavy sun light, wear clothes and hats and use suns cream with SPF (sun protection factor) to protect our skin.

Question 37

why do skiers and mountaineers wear sun glasses/

Answer 37

they would get temporary ‘snow blindness” because snow reflects a lot of light from the sun, so therefore wearing glasses protects their eyes.

Question 38

name two radiations that have a higher frequency than ultraviolet radiation.

Answer 38

gamma radiations and x-ray radiations

Question 39

what happens if you are exposed to a huge amount of x-ray and gamma rays?

Answer 39

it would cause a mutations in DNA, which will kill our body cells and cause cancer.