4. Waves

Question 1

Simple harmonic motion

Answer 1

When the direction of the force is always towards the fixed point and the magnitude is proportional to the displacement from the fixed point.

Question 2

Time period (SHM)

Answer 2

The time taken for a complete cycle.

Question 3

Frequency (SHM)

Answer 3

The number of complete cycles per second.

Question 4

Amplitude (SHM)

Answer 4

The maximum displacement of the particle.

Question 5

Displacement (SHM)

Answer 5

The displacement of the particle from the equilibrium position (in single direction).

Question 6

Phase difference

Answer 6

The x shift between two sin waves.

Question 7

Isochronous oscillations

Answer 7

Oscillations with the same time period no matter what amplitude change changes due to damping occur.

Question 8

Travelling wave

Answer 8

A wave that transfers energy form one place to another.

Question 9

Wavelength (waves)

Answer 9

The shortest distance between two points that are in phase.

Question 10

In phase

Answer 10

Two particles are in phase if they are moving in the same direction at the same time (an integer no of wavelengths apart)

Question 11

Frequency (waves)

Answer 11

The number of peaks/troughs passing a point per second OR the number of vibrations per second performed by the source.

Question 12

Period (waves)

Answer 12

The time taken for a complete wavelength to pass a point OR a particle to undergo one complete oscillation.

Question 13

Wave speed

Answer 13

The speed at which a point on a wave is moving through a medium.

Question 14

Transverse

Answer 14

A wave where the direction of oscillation is perpendicular to the direction of energy transfer.

Question 15

Longitudinal

Answer 15

A wave where the direction of oscillation is parallel to the direction of energy transfer.

Question 16

Wavefront

Answer 16

A surface that travels with a wave and is perpendicular to the direction of movement.

Question 17

Ray

Answer 17

A line showing the direction of energy transfer and is perpendicular to the wavefront.

Question 18

Amplitude (waves)

Answer 18

The maximum displacement of a vibration or oscillation, measured from the position of equilibrium.

Question 19

Intensity

Answer 19

The power transferred per unit area.

Question 20

Superposition

Answer 20

When two waves meet at a point the resultant amplitude is the vector some of the amplitudes of the two waves.

Question 21

Polarization

Answer 21

the action of restricting the vibrations of a transverse wave, especially light, wholly or partially to one direction.

Question 22

Plane polarized

Answer 22

When the direction of vibration stays constant over time

Question 23

Partial polarization

Answer 23

When there is some restriction to the direction of vibration but not 100%.

Question 24

Malus’s Law

Answer 24

When plane polarised light is incident on an analyser, the intensity of the light transmitted by the analyser is directly proportional to the square of the cosine of the angle between the transmission axes of the analyser and the polariser. I is prop to 1/cos^2(theta)

Question 25

Optically active

Answer 25

The ability to rotate the plane of plane polarized light.

Question 26

Polarimeter

Answer 26

Measures angle light is rotated.

Question 27

Huygen’s principle

Answer 27

Every point on a wavefront is a source of wavelets. These wavelets spread out in the forward direction, at the same speed as the source wave. The new wavefront is a line tangent to all of the wavelets.

Question 28

Absolute refractive index

Answer 28

the ratio of the speed of light in a vacuum to that in the given medium

Question 29

Snell’s law

Answer 29

for waves of a particular frequency and for a chosen pair of media the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant called the refractive index.

Question 30

total internal reflection

Answer 30

the complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle.

Question 31

 Coherent light =

Answer 31

light with the same frequency/wavelength that are in phase.

Question 32

 Diffraction =

Answer 32

the bending of a wave as it passes around an object or through a slit.

Question 33

 Path difference =

Answer 33

the difference in distance travelled by two waves that meet at a point.

Question 34

node

Answer 34

a point on a standing wave where interference is destructive

Question 35

antinode

Answer 35

a point on a standing wave where interference is constructive.

Question 36

standing wave

Answer 36

a wave where the positions of the peaks and troughs do not change.