Waves 🌊

Question 1

Transverse wave

Answer 1

a wave in which the oscillations are perpendicular to the direction of energy transfer

Question 2

Longitudinal wave

Answer 2

a wave in which the oscillations are parallel to the direction of energy transfer

Question 3

Coherent waves

Answer 3

waves with a constant phase difference

Question 4

Time period (T)

Answer 4

time taken for one complete wave cycle, in this time the wave travels one wavelength

Question 5

Frequency

Answer 5

the number of wave cycles passing a point per unit time

Question 6

Wavelength

Answer 6

the minimum distance between two in phase points on adjacent waves

Question 7

State the principle of superposition

Answer 7

When two or more waves meet at a point in space the resultant displacement is the vector sum of the displacements of the original waves

Question 8

Displacement

Answer 8

the distance in a particular direction of a point/particle from the equilibrium position

Question 9

Amplitude

Answer 9

maximum displacement from the equilibrium position

Question 10

Wave speed

Answer 10

distance travelled by the wave per unit time

Question 11

Phase

Answer 11

measure of the position of a certain point along the wave cycle

Question 12

Define phase difference

Answer 12

how out of sync two waves are

Question 13

Progressive wave

Answer 13

A wave which transfers energy as a result of the oscillations of the particles/medium it moves through

Question 14

Radio waves

Answer 14

> (10^-1)m

Question 15

Microwaves

Answer 15

(10^-1)-(10^-3)m

Question 16

Infrared

Answer 16

(10^-3)-(7*10^-7)m

Question 17

Visible light

Answer 17

(7x10^-7)-(4x10^-7)m

Question 18

Ultraviolet

Answer 18

(4*10^-7)-(10^-8)m

Question 19

X-rays

Answer 19

(10^-8)-(10^-13)m

Question 20

Gamma rays

Answer 20

<(10^-10)m

Question 21

Define ‘interference’

Answer 21

When two waves meet/overlap there is a change in the overall displacement

Question 22

Why does light need to be monochromatic in the young double slit experiment?

Answer 22

In order to be coherent, if light is not monochromatic the waves aren’t coherent and the fringe pattern disappears

Question 23

Explain why sound waves cannot be plane polarized

Answer 23

• Polarized waves can only oscillate in one plane which is perpendicular to the direction of energy transfer
• Sound waves are longitudinal so oscillate parallel to the direction of energy transfer
• Hence, cannot be confined to a single perpendicular plane

Question 24

Why do maxima form in a double slit experiment?

Answer 24

Waves arrive in phase so interfere constructively (producing a maxima)

Question 25

Why do minima form in a double slit experiment?

Answer 25

Waves arrive in antiphase so interfere destructively (forming a minima)

Question 26

Define **intensity**

Answer 26

Power per unit area perpendicular to the direction of energy transfer

Question 27

Describe how you can demonstrate in the laboratory that light is plane polarised

Answer 27

- Place a polarising filter in front of the light - Rotating the filter will change the intensity of the light - e.g. when filter perpendicular to plane of oscillation no light is transmitted