Oscillations + Wave Motion

Question 1

Simple Harmonic Motion

Answer 1

The motion of a particle about a fixed point such that its acceleration is proportional to its displacement from the fixed point and is always directed towards the point

Question 2

Angular Frequency (w)

Answer 2

The rate of change of phase angle of oscillation, and is equal to the product of 2pi and its frequency

Question 3

Amplitude

Answer 3

The magnitude of the maximum displacement of the particle from its equilibrium position

Question 4

Period

Answer 4

The time taken to complete one oscillation

Question 5

Free Oscillations

Answer 5

If an object is displaced from its equilibrium position and then released it oscillates at its natural frequency about the equilibrium position

Question 6

Damping

Answer 6

The process whereby energy is removed from an oscillating system

Question 7

Light damping

Answer 7

Light damping results in oscillations whereby the amplitude decays exponentially with time. the frequency of oscillation is slightly smaller than the undamped frequency

Question 8

Heavy damping

Answer 8

Heavy damping results in no oscillation and the system takes a long time to return to its equilibrium position

Question 9

Critical damping

Answer 9

Critical damping results in no oscillation and the system returns to its equilibrium position in the shortest time.

Question 10

Resonance

Answer 10

Resonance occurs when a system responds at maximum amplitude to an external driving force. This occurs when the frequency of the driving force is equal to the natural frequency of the driven system

Question 11

Malus’s Law

Answer 11

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

I = Io(costheta)^2

Question 12

Wavelength

Answer 12

The distance between two consecutive points which are in phase

Question 13

Frequency

Answer 13

The number of oscillations made per unit time

Question 14

Progressive wave

Answer 14

A wave that transports energy from one point to another in the direction of wave propagation

Question 15

Transverse wave

Answer 15

A wave in which its particles oscillate in a direction perpendicular to the direction of energy transfer

Question 16

Longitudinal wave

Answer 16

A wave in which its particles oscillate in a direction parallel to the direction of energy transfer

Question 17

Wavefront

Answer 17

A line or surface joining points on a wave that are in phase. The wave travels in a direction perpendicular to these wavefronts

Question 18

Phase Difference

Answer 18

The phase difference between to particles in a wave or between two waves at a point is a measure of the fraction of a cycle which one is ahead of the other

Question 19

Inverse Square Law

Answer 19

If the power of the source is constant, then the intensity is inversely proportional to the square of the distance from the source.

Question 20

Phase angle

Answer 20

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

Question 21

In phase

Answer 21

Particles of a wave are considered in phase when they execute the same motion at the same time

Question 22

Anti phase

Answer 22

Particles of a wave are considered to be in antiphase when they execute motions that are out of phase by pi radians or 180 degrees

Question 23

Out of phase

Answer 23

Particles of a wave that show different stages of motion. They have non zero phase difference