11 Waves

Question 1

Progressive wave

Answer 1

A wave which energy is transferred from one point to another via vibrations or oscillations within the wave

Question 2

Amplitude

Answer 2

Magnitude of the maximum displacement of an oscillating particle from its equilibrium position.

Question 3

Period, T

Answer 3

Time elapsed between successive occasions when a particle is moving through the same point in the same direction.

Question 4

Frequency, f

Answer 4

Number of oscillations made per unit time

Question 5

Wavelength, λ

Answer 5

Shortest distance between two points on a progressive wave which are in phase

Question 6

Wavefront

Answer 6

Locus of points having the same phase

Question 7

speed of the wave = ?

Answer 7

distance travelled by the wave/time taken
v = λ/T
=f λ

Question 8

Phase

Answer 8

An angle which gives a measure of the fraction of the cycle that has been completed by an oscillating particle/wave

Question 9

∆ Φ = ?

Answer 9

(2 π/λ) ∆x

OR

(2 π/T) ∆t

Question 10

Intensity (I)

Answer 10

Wave energy incident per unit time per unit area normal to the wave
Power/ Area

Question 11

Relationship between I and Amplitude

Answer 11

I proportional to Amplitude^2
Since I ∝E, E= 1/2 m(ω^2)(A^2)

Question 12

Relationship between intensity and distance from wave source

Answer 12

I inversely proportional to r^2 (3D)
I inversely proportional to r (2D)

Question 13

Polarisation

Answer 13

The confinement of oscillations in only one plane. Plane of oscillations is parallel to direction of energy transfer

(Only transverse waves can be polarised)

Question 14

Malus’ Law

Answer 14

The intensity of a beam of plane-polarised light after passing through a rotatable polariser is directly proportional to the square of the cosine of the angle which the polariser is rotated from the position that gives maximum intensity

I = I(max) cos^2 θ