Extra

Question 1

What is monochromatic light?

Answer 1

• Light that has a single frequency
• A laser light is an example of a monochromatic light

Question 2

What are the conditions for total internal reflection?

Answer 2

• The medium is entering a substance with a lower optical density
• The critical angle is exceeded

Question 3

What do Optical Fibre do?

Answer 3

Optical fibres transmit light by total internal reflection.

Question 4

What are the key features of an optic fibre?

Answer 4

• Core
• Cladding
• Protective Coating

Question 5

What are optical fibres used for?

Answer 5

• Internet providers use optical fibres to set up quick and reliable internet connections.
• They can be used for endoscopy

Question 6

Do optical fibre lose lots of information?

Answer 6

No they don’t they are able to transmit huge amounts of information with few information losses

Question 7

What is a thin converging lens?

Answer 7

• A thin converging lens (curved piece of glass) causes parallel rays of light that pass through it to converge (come together).
• When a beam of light strikes a thin converging lens, the light is refracted twice.

Question 8

What is the image produced by a conveging lens like when the object is more than two focal lengths from the centre of the lens?

Answer 8

• The image is real
• The image is inverted
• The image is diminished (smaller than the object)
• Examples: the eye and cameras

Question 9

What is the focal length?

Answer 9

The focal length is the distance from the centre of the lens to the principal focus

Question 10

What is the optical axis?

Answer 10

• The optical axis is an invisible line at 90 degrees to the face of the lens that passes through the lens’ centre.
• Light travelling along the optical axis passes through the centre of the lens without being deviated.

Question 11

What is the principal focus?

Answer 11

• Light rays that are parallel to the optical axis pass through the lens and converge (come together) at the principal focus.
• There is one principal focus on each side of the lens as light can pass through the lens in either direction.

Question 12

What is the image produced by a conveging lens like when the object is between one and two focal lengths from the centre of the lens?

Answer 12

• The image is real
• The image is inverted (upside down)
• The image is magnified (larger than the object)
• Examples are the projector and the photocopier

Question 13

What is the image produced by a conveging lens like when the object is two focal lengths from the lens

Answer 13

• The image is the same size as the object

Question 14

What is the image produced by a conveging lens like when the object is between the principal focus and the centre of the lens?

Answer 14

• The image is erect (the right way up)
• The image is Virtual
• The image is magnified
• The image is also on same side of the lens as the object
• Am example is a magnifying glass

Question 15

What is the dispersion of light?

Answer 15

• Dispersion is the seperation of white light into a spectrum (range) of colours
• A rainbow is an example of a spectrum that is formed when sunlight is dispersed by raindrops.

Question 16

What are the safety precautions taken while using X-Rays?

Answer 16

• Due to the dangerous nature of X-rays, exposure to X-rays should always be kept to a minimum.
• People working with X-ray equipment should always shield themselves to prevent exposure to X-rays.
• These people will place materials (metals for example lead) between themselves and the X-rays.

Question 17

What are the risks of Infra-red radiation

Answer 17

• Infra-red radiation can cause serious skin burns if emitted from high-intensity sources.

Question 18

What are the risks of microwaves (the actual wave)?

Answer 18

• Because humans are largely made up of water, exposure to microwaves could have a harmful effect.

Question 19

What are risks of radio waves?

Answer 19

• At high intensities, radio waves can cause internal heating of living tissue with potentially harmful effects.

Question 20

What are sound waves?

Answer 20

• Sound waves are longitudinal waves.
• Sound is produced by the vibration of particles in a medium (the substance that waves travel through).
• The vibrations mean that sound waves travel in a series of compressions (where the medium is squashed together) and rarefactions (where the medium is stretched apart).