Waves

Question 1

What is the EM spectrum?

Answer 1

The full range of frequencies of EM waves, from gamma rays to radio waves

Question 2

Define amplitude

Answer 2

The maximum displacement from the equilibrium position

Question 3

Define frequency

Answer 3

The number of wavelengths passing a given point per unit time

Question 4

What is the wave equation?

Answer 4

Wavespeed = wavelength x frequency

Question 5

Define wave intensity

Answer 5

The radiant power passing through a surface per unit area

Question 6

Define reflection

Answer 6

The change of direction of a wave at a boundary between two different media, so that the wave remains in the original medium

Question 7

n(refractive index) =

Answer 7

c(speed of light in a vacuum)/v(speed of light in a material)

Question 8

The critical angle is:

Answer 8

The angle at which light is refracted at 90 degrees

Question 9

What is TIR?

Answer 9

When all of the incident light is reflected at a boundary going into a medium of lower refractive index

Question 10

Diffraction is:

Answer 10

The phenomenon in which waves passing through a gap or around an obstacle spread out

Question 11

Polarisation is:

Answer 11

The phenomenon in which oscillations of a transverse wave are limited to only one plane

Question 12

Polarisation can only occur in

Answer 12

Transverse waves

Question 13

Uses of polarisation include

Answer 13

Ariel
Stress analysis
Polaroid filters

Question 14

The principle of superposition states

Answer 14

When two similar types of wave meet at a point the resultant displacement at that point is equal to the sum of the displacement of the individual waves

Question 15

What is interference?

Answer 15

The superposition of two progressive waves from coherent sources to produce a resultant wave with a displacement equal to the sum of the individual displacements from the two waves

Question 16

Phase difference is

Answer 16

The difference between the displacements of particles along a wave, measured in degrees or radians, with each complete cycle represented 360 degrees or 2pi radians

Question 17

Coherence is

Answer 17

Two wave sources, or waves, that have a constant phase difference

Question 18

Destructive interference is

Answer 18

Superposition of two waves in antiphase so that the waves cancel each other out and the resultant wave has a smaller amplitude than the original wave

Question 19

Constructive interference

Answer 19

Is superposition of two waves in phase so that the resultant wave has a greater amplitude

Question 20

Path difference

Answer 20

Is the difference in the distance travelled by two waves from their source to a specific point

Question 21

Powers of typical wavelengths of em spectrum

Answer 21

Radio - 3
micro - -2
infrared - -5 
visible - 7 x 10^-7 - 4 x 10^-7
ultra violet - -7
x rays - -9 
gamma rays - -14

Question 22

What is difference between the amplitude of a progressive and stationary wave?

Answer 22

progressive - All parts of the wave have the same amplitude ( assuming no energy losses)
Stationary - Maximum amplitude occurs at the antinode and then drops to zero at the node

Question 23

In a stationary wave all parts of the wave between two nodes are …

Answer 23

in phase

Question 24

In a stationary wave all parts of the wave on either side of a node are …

Answer 24

in anti phase

Question 25

What is a harmonic?

Answer 25

An integer multiple of the fundamental frequency