4.3 Wave Characteristics

Question 1b

Marks: 1

(b)

Complete the following sentence by placing a tick (✓) next to the correct answer:

The distance between two consecutive wavefronts is equal to the:

	wavelength
	frequency
	amplitude

[1]

Key Concepts

Question 1c

Marks: 4

(c)

On the grid below, draw scale diagrams showing the wavefronts for

(i)

A plane wave with a wavelength of 1 cm.

[2]

(ii)

A circular wave with a wavelength of 1 cm.

[2]

On both diagrams, show with arrows, the direction of propagation.

8-1-ib-sl-sq1c-q-grid

Key Concepts

Question 1d

Marks: 2

(d)

Complete the following sentences by circling the correct word:

The higher the frequency of an oscillation, the longer / shorter the wavelength and the closer / further apart the wavefronts are to / from one another.

The lower the frequency of the oscillation, the longer / shorter the wavelength and the closer / further apart the wavefronts are to / from one another.

[2]

Key Concepts

Question 2a

Marks: 2

(a)

Match the terms power and intensity to their correct definitions and SI units.

[2]

Key Concepts

Question 2b

Marks: 2

A point source radiates light waves in all directions. The intensity, I, of the waves is related to the power, P, by the equation:

$I = \frac{P}{4 π r^{2}}$

The relationship between the distance from the point source, r, and the intensity of the wave are shown to follow an inverse square law.

(b)

Describe what is meant by the term inverse square law in this context.

[2]

Key Concepts

Question 2c

Marks: 2

(c)

Describe the relationship between intensity, I, and amplitude, A.

[2]

Key Concepts

Question 2d

Marks: 2

Two students are investigating the relationship between intensity and amplitude. The graphs below show the variation of the displacement of a particle with time when two progressive waves X and Y pass separately through a medium.

4-3-q2d-question-stem-sl-sq-easy-phy

The intensity of wave X is I₀. Student 1 says that the intensity of wave Y must be $\frac{I_{0}}{2}$ but Student 2 thinks it must be $\frac{I_{0}}{4}$ .

(d)

Determine, using the relationship from part (c), which student is correct.

[2]

Key Concepts

Question 3a

Marks: 2

(a)

Outline what is meant by the principle of superposition.

[2]

Key Concepts

Question 3b

Marks: 1

Two pulses travel toward one another as shown in the diagram.

4-3-3b-question-stem-sl-sq-easy-phy

(b)

Sketch the resultant displacement as the pulses superpose.

[1]

Key Concepts

Question 3c

Marks: 1

Two pulses travel in opposing directions as shown in the diagram. When the pulses meet, they superpose.

4-3-3c-question-stem-sl-sq-easy-phy

(c)

Draw the resultant peak as the pulses superpose.

[1]

Key Concepts

Question 3d

Marks: 4

(d)

Distinguish between the terms constructive interference and destructive interference.

[4]

Key Concepts