Topic 5-Light and the electromagnetic spectrum

Question 1

What is the law of reflection?

Answer 1

The angle of incidence will be the same as the angle of reflection.

Question 2

When will light bend towards the medium?

Answer 2

When light goes into a medium where it will travel slower.

Question 3

What is total internal reflection?

Answer 3

When the light is completely reflected inside the glass.

Question 4

What is the difference between refraction, critical angle and total internal reflaction?

Answer 4

Question 5

What is the critical angle?

Answer 5

The angle if incidence at which the light is no longer refracted.

Question 6

Explain the core practical on investigating refraction.

Answer 6

Question 7

What is the difference between specular and diffuse reflection?

Answer 7

Question 8

How do you see luminous objects?

Answer 8

Light from them enters your eyes.

Question 9

What is white light?

Answer 9

Light from bulbs or the sun and is made up of all colours of a rainbow.

Question 10

How do prims work?

Answer 10

Each colour that makes up white light has a different frequency so they travel at a different speed and therefore refract differently.

Question 11

What is a lens?

Answer 11

A lens is a piece of transparent material shaped to refract light in particular ways. The power describes how much it bends light.

Question 12

What is the triangle linking image size, actual size and magnification?

Answer 12

Question 13

What is the triangle linking power and focal length?

Answer 13

Question 14

What is a converging/convex lens?

Answer 14

Question 15

What is a diverging/concave lens?

Answer 15

Question 16

Explain transparent, translucent and opaque.

Answer 16

Question 17

What is a real image?

Answer 17

When the rays of light cross when drawing a ray diagram. This means it can be projected onto a screen.

Question 18

What is a virtual image?

Answer 18

When the rays do not cross when drawing the ray diagram. This means the image must be traced back to the other side of the lens/mirror and where they meet there will be where the image appears to be. A magnifying glass is an example of this.

Question 19

What are diminished and magnified images?

Answer 19

Diminished-the image produced is smaller than the original object

Magnified-if the image is larger than the original image

Question 20

What are inverted and erect images?

Answer 20

inverted-image formed on opposite side of principle axis

erect-same side of principle axis

Question 21

What can convex/converging lenses form?

Answer 21

Question 22

What can concave/diverging lenses form?

Answer 22

Question 23

Can you draw a lens diagram?

Answer 23

If you can’t go fucking learn you fat prick!

Question 24

Are lower frequencies red or blue?

Answer 24

Red

Question 25

What is the order of electromagnetic waves?

Answer 25

Question 26

What are the uses of infared radiation?

Answer 26

Communication at short ranges, a grill or a toaster or security systems with sensors that can detect infared radaition emitted by intruders.

Question 27

What are the uses of microwaves?

Answer 27

Satellite transmissions such as mobile phone signals or a microwave oven.

Question 28

What are the uses of radio waves?

Answer 28

Transmitting radio broadcasts and TV programmes as well us other communications. Controllers on the ground communicate with spacecraft using radio waves.

Question 29

What are radio waves produced by?

Answer 29

Oscillations in electrical circuits. A metal rod or wire can be used as an ariel to receive radio waves as they absorb them and cause oscillations.

Question 30

Why is there a maximum range for microwave communications?

Answer 30

The curved curface of the earth gets in the way.

Question 31

Which colour stars are the hottest?

Answer 31

Question 32

What is the amount of energy transferred in a certain time?

Answer 32

Power.

Question 33

How does the earth balance it’s energy?

Answer 33

It absorbs about half the radiation and re-radiated this energy as infrared radiation which can warm up the atmosphere. It must radiate energy into space at the same rate it is absorbed to keep a constant temperature.

Question 34

Why would greenhouse gasses being removed from the atmosphere decrease the temperature of the earth?

Answer 34

The atmoshphere would be able to hold less energy and the temperature would decrease.

Question 35

Explain the core practical on investigating radiation.

Answer 35

Question 37

What are the uses for ultraviolet?

Answer 37

It can disinfect water by killing microorganisms in it. Some materials absorb ultraviolet and re-emit it as visible light. This is called fluorescence and can be uses in security markings.

Question 38

What can x-rays be used for?

Answer 38

X-rays can pass through muscles and fat easily but not so much bone, this means it can be used in medicine to make images of inside the body or examine the insides of metal objects to inspect luggage at airports.

Question 39

What can gamma rays be used for?

Answer 39

They can sterilise food and surgical equipment by killing microorginisms. They can also kill cancer cells in radiotherapy.

Question 40

What are some of the dangers of EM waves?

Answer 40

Microwaves heat water and our body is mostly water so it could heat us. Too much infrared radiation could burn our skin. Ultraviolet can cause sunburn. X-rays and gamma rays can cause mutations in our DNA that can kill cells or cause cancer.

Question 41

What are 2 advantages of using a camera rather than an eye for studying stars?

Answer 41

You can zoom in and get permanant evidence.

Question 42

Why does the ray not change direction when it enters the glass?

Answer 42

It is entering at the normal.

Question 43

What happens when waves go to shallow water?

Answer 43

The wavelength decreases.

Question 44

What are some advantages of using gamma radiation to destroy tumours?

Answer 44

It is painless, accurate, no surgery is required and no radioactive substances are left in the body.