Waves

Question 1

What is a progressive wave?

Answer 1

A progressive wave transfers energy without transferring material

Question 2

What is amplitude

Answer 2

A waves maximum displacement from the equilibrium position

Question 3

What is frequency

Answer 3

The number of complete oscillations passing through a point per second

Question 4

What is wavelength

Answer 4

The length of one whole oscillation

Question 5

What is phase

Answer 5

The position of a certain point on a wave cycle

Question 6

What is phase difference

Answer 6

How much a particle/wave lags behind another particle/wave

Question 7

If two points are in phase what characteristics are the same?

Answer 7

They will have the same displacement and velocity- this is caused by having the same frequency and wavelength

Question 8

What are the properties of a transverse wave?

Answer 8

particles traverse at right angles to the direction of energy transfer

Question 9

What are the properties of a longitudinal wave?

Answer 9

Oscillation of particles is parallel to the direction of energy transfer

Question 10

What is superposition

Answer 10

Where the displacements of two waves are combined as they pass each other, with the result being a vector sum of each waves displacement

Question 11

What is constructive interference?

Answer 11

When two waves have displacement in the same direction

Question 12

What is destructive interference?

Answer 12

When one wave has a positive displacement and the other has negative displacement

Question 13

What is total destructive interference?

Answer 13

When the waves have equal and opposite displacement total destructive interference occurs

Question 14

How is a stationary wave formed?

Answer 14

When 2 progressive waves that are travelling in opposite directions with the same frequency, wavelength and amplitude superpose

Question 15

When does refraction occur?

Answer 15

When a wave enters a different medium causing it to change direction, either towards or away from the normal.

Question 16

What is snells law?

Answer 16

n1sin0 = n2sin0

Question 17

If a ray of light travels into a more optically dense medium will the light beam move towards or away from the normal.

Answer 17

Bend towards the normal.

Question 18

When does TIR occur?

Answer 18

Total internal reflection occurs when the angle of incidence is greater than the critical angle and the incident refractive index is greater than the refractive index of the material at the boundary.

Question 19

What its absorption?

Answer 19

Where part of the signals energy is absorbed by the fibre, reducing the amplitude of the signal which can lead to the loss of information.

Question 20

What is dispersion?

Answer 20

Dispersion causes pulse broadening, which is where the received signal is broader than the original transmitted signal.

Question 21

What is modal dispersion?

Answer 21

When light rays enter the fibre at different angles this causes the rays to take a different amount of time to reach the end of the fibre causing pulse broadening.

Question 22

What is material dispersion?

Answer 22

When lights of different wavelengths are sent along a fibre, they travel at different speeds along the fibre leading to pulse broadening.

Question 23

How can absorption and dispersion be reduced?

Answer 23

By using an optical fibre repeater, which regenerates the signal during its travel to its destination