Simplified P1 - Spectrum of Waves & Light and Lasers

Question 1

What is the amplitude of a wave?

Answer 1

The amplitude of a wave is the maximum displacement of a particle from its rest position.

Question 2

What is the crest of a wave?

Answer 2

The crest of wave is the highest point a wave above its rest position

Question 3

What is the trough of a wave?

Answer 3

A trough of a wave is the lowest point on a wave below its rest position.

Question 4

What is the wavelength of wave?

Answer 4

The wavelength of a wave is the distance between two successive points on a wave having the same displacement and moving in the same direction.

Question 5

What is the frequency of a wave?

Answer 5

The frequency of wave is the number of complete waves passing a point in one second.

Question 6

What is the equation for the speed of a wave?

Answer 6

The equation for the speed of a wave is:

Wave speed = frequency x wavelength

Question 7

What is the order of waves on the electromagnetic spectrum in order from highest frequency to lowest frequency?

Answer 7

In order of highest to lowest:
Gamma Radiation
X Rays
Ultraviolet Radiation
Visible Light
Infrared Radiation
Microwaves 
Radio Waves

Question 8

What is the order of waves on the electromagnetic spectrum in order from shortest wavelength to longest wavelength?

Answer 8

In order from highest to lowest:
Gamma Radiation
X Rays
Ultraviolet Radiation
Visible Light
Infrared Radiation
Microwaves 
Radio Waves

Question 9

What is a plane mirror?

Answer 9

A plane mirror is a mirror with a flat (planar) reflective surface

Question 10

How many plane mirrors does a periscope have?

Answer 10

A periscope is an example of an optical instrument, it uses two or more plane mirrors.

Question 11

What is refraction?

Answer 11

Sound waves and light waves change speed when they pass across the boundary between two substances with different densities, such as air and glass. This causes them to change direction and this effect is called refraction.

Question 12

Why does refraction occur?

Answer 12

Refraction occurs because the speed of waves decreases as the wave enters a more dense medium and increases as the wave enters a less dense medium. The frequency stays the same but the wavelength changes.
See picture for reference
http://sciencelearn.org.nz/var/sciencelearn/storage/images/contexts/light-and-sight/sci-media/images/refraction-of-light-in-water/685295-1-eng-NZ/Refraction-of-light-in-water.jpg

Question 13

What is Diffraction?

Answer 13

Diffraction is the spreading out of a wave as it passes through a gap.
See picture for reference:
http://www.bbc.co.uk/staticarchive/31d29a61aab276481d40a6f7faa903eb36a59af3.jpg

Question 14

What can cause variation in the amount of diffraction?

Answer 14

The amount of diffraction depends on he size of the gap; the most diffraction occurs when the gap is a similar size to the wavelength, larger gaps show less diffraction, if the wavelength is equal to the gap size then the most diffraction will occur; Diffraction effects are noticeable in telescopes and microscopes.

Question 15

How does Morse Code work?

Answer 15

Morse code uses series of dots and dashes to represent different letters of the alphabet, Morse Code can be used by signalling lamps as a series of short and long flashes of light, Morse code is an example of a Digital Signal.

Question 16

How fast is a signal sent by light, electricity, microwaves or a radio wave?

Answer 16

When a signal is sent by light,electricity,microwaves or radio waves it is almost instantaneous.

Question 17

What are some factors that must be considered for each method of sending signals?

Answer 17

Each method of transmission has disadvantages and advantages, these must be considered:

• Can the signal be seen by others?
• Can the wires be cut?
• How far does the signal have to travel?

Question 18

What is white light?

Answer 18

White light is light made up of different colors of different frequencies out of phase , it contains all the wavelengths of the visible spectrum at equal intensity.

Question 19

What is a characteristic of laser light?

Answer 19

Laser light has only a single frequency, is in phase Unlike white light and shows low divergence.

Question 20

How does laser light read from the surface of a compact disc?

Answer 20

• The surface of the CD is pitted
• The pits represent the digital signal
• Laser light is shone onto the CD surface and the difference in reflection provides the information for the Digital Signal.

Question 21

What happens when light travels from one material to another?

Answer 21

When light travels from one material to another, it is normally refracted.

Question 22

What happens when light passes from a more dense material into a less dense material?

Answer 22

If light is passing from a more dense material into a less dense, the angle of refraction is larger than the angle of incidence.

Question 23

What happens when the angle of refraction is 90 degrees?

Answer 23

When the angle of refraction is 90°, the angle of incidence is called the critical angle.

Question 24

What happens if the angle of incidence is bigger than the Critical angle?

Answer 24

If the angle of incidence is bigger than the critical angle, the light is reflected, this is called total internal reflection.

Question 25

Telephone conversations and computer data are transmitted long distances through what kind of cable and at what speed?

Answer 25

Telephone conversations and computer data are transmitted long distances along optical fibres at the speed of light (200000 km/s in glass).

Question 26

What is one way to improve reflection in optic fibres?

Answer 26

Some fibres can be coated to improve reflection.

Question 27

What is an advantage of using optic fibers?

Answer 27

Optical fibres can carry more information than an ordinary cable of the same thickness. The signals in optical fibres do not weaken as much over long distances as the signals in ordinary cables

Question 28

What is an endoscope?

Answer 28

an instrument which can be introduced into the body to give a view of its internal parts such as organs.

Question 29

What can an endoscope be used for?

Answer 29

An endoscope allows doctors to see inside a body without the need for surgery.

Question 30

How does an endoscope work?

Answer 30

• Light passes along one set of optical fibres to illuminate the inside of the body.
• The light is reflected.
• The reflected light passes up another set of fibres to an eyepiece or camera.