Chapter 4 - Waves

Question 1

What are the two types of waves?

Answer 1

Longitudinal waves and transverse waves.

Question 2

What are electromagnetic waves?

Answer 2

Waves with oscillating electric and magnetic fields.

Question 3

What are longitudinal waves?

Answer 3

Waves which oscillate parallel to the direction of energy transfer.

Question 3

When is a transverse wave polarised?

Answer 3

When oscillations stay in one plane only.

Question 3

What are transervse waves?

Answer 3

Waves which oscillate perpendicular to the direction of energy transfer.

Question 4

What do polarising filters affect?

Answer 4

Light intensity.

Question 5

What is the displacement of a vibrating particle?

Answer 5

The displacement from equilibrium position.

Question 6

What is the amplitude of a wave?

Answer 6

The maximum displacement of a vibrating particle. Distance between equilibrium position and peak or trough.

Question 7

What is the wavelength?

Answer 7

The distance between the same point on two adjacent waves. It is the complete cycle of a wave.

Question 8

What is the period of a wave?

Answer 8

The time for one complete wave to pass a fixed point.

Question 9

What is the frequency of a wave?

Answer 9

The number of complete waves passing a point per second, measured in Hz.

Question 10

Equation for frequency.

Answer 10

f = 1/T, where T is the period.

Question 11

What is the phase of a vibrating particle?

Answer 11

The fraction of the cycle the particle has completed since the start of the cycle.

Question 11

Wave speed equation.

Answer 11

Wave speed, c = frequency X wavelength

Question 12

What is the phase difference?

Answer 12

The fraction of a cycle between the vibrations of two particles, measured in degrees or radians. The two particles must be vibrating at the same frequency.

Question 13

Phase difference equation.

Answer 13

Phase difference in radians = (2πd)/λ
Where d is the distance between particles and λ is the wavelength.

Question 14

What are wavefronts?

Answer 14

The waves observed in a ripple tank which are lines of constant phase. Waves travel at right angles to the wavefront.

Question 15

What is refraction?

Answer 15

When waves pass a boundary, causing them to change direction and speed.

Question 16

What is diffraction?

Answer 16

When waves spread out after passing through a gap.

Question 17

What is the principle of superposition?

Answer 17

The principle of superposition states that when two waves meet, the total displacement at a point is equal to the sum of the individual displacements at that point.

Question 18

What are stationary waves?

Answer 18

Wave patterns with nodes and antinodes formed when two or more progressive waves of the same frequency and amplitude pass through each other.

Question 19

What are progressive waves?

Answer 19

Waves which travel through a substance or through space if electromagnetic.

Question 20

What is interference?

Answer 20

When waves are passing through each other with constant frequency and at a constant phase difference, causing cancellation and reinforcement at fixed positions.

Question 21

What are coherent sources of waves?

Answer 21

Sources which vibrate at the same frequency and with constant phase difference.

Question 22

What is a node?

Answer 22

A point on a harmonic of no displacement.

Question 23

What is an antinode?

Answer 23

A point midway between nodes of a harmonic where amplitude is maximum.

Question 24

Distance between adjacent nodes = Wavelength/2

Answer 24

Distance between adjacent nodes = Wavelength/2

Question 25

Stationary waves that vibrate freely do not transfer energy to their surroundings.

Answer 25

Stationary waves that vibrate freely do not transfer energy to their surroundings.

Question 26

Fundamental frequency, f1 = c/2L

Frequency of nth harmonic = nf1

Answer 26

Fundamental frequency = c/2L

Frequency of nth harmonic = nf1