CAIE Physics: Waves (Ch 7) flashcards

Contains definitions on the waves topic. Most definitions are from the textbook. All the flashcards are for chapter 7 in the textbook (No superposition)

Define displacement

The distance of a point on the wave from its undisturbed/ equilibrium position.

Define amplitude

The amplitude is the maximum displacement of a wave.

Define phase difference

The difference in the phases of two oscillating particles, measured in degrees or radians.

Define period

The time taken to make one complete oscillation.

Define frequency

The number of oscillations per unit time of a point in a wave.

Define wavelength

The distance between two adjacent points on a wave oscillating in step with each other.
OR the distance between two adjacent wavefronts.

Define speed

The distance travelled by a wave per unit time.

What is the formula linking intensity, power, and area

Intensity = Power / Area

What is the relationship between intensity and amplitude

Intensity is proportional to (amplitude)²

What is the range of wavelengths of radio waves in metres?

Just above 10⁶ to 0.1

What is the range of wavelengths of microwaves in metres?

10^-1 to 10^-3

What is the range of wavelengths of infrared in metres?

10^-3 to 7x10^-7

What is the range of wavelengths of visible light in metres?

7x10^-7 (red) to 4x10^-7 (violet)

What is the range of wavelengths of UV in metres?

4x10^-7 to 10^-8

What is the range of wavelengths of X-Rays in metres?

10^-8 to 10^-13

What is the range of wavelengths of gamma waves in metres?

10^-10 to 10^-16

What is the principle of superposition

When (two) waves meet/overlap, the resultant displacement is the sum of the displacements of each wave.

NOTE: meet is preferred but just write “meet or overlap”

Define coherence

When there is a constant phase difference (between waves/ wavefronts)

Define interference

It is the sum of displacements of overlapping waves.

Describe the diffraction of light waves. [2 marks]

When waves are incident on a slit/gap/edge of an obstacle,
they spread out into a geometrical shadow.

Explain what is meant by a node of a stationary wave [1 mark]

Point where there is zero amplitude

Note: MS from 2020

State what is meant by the diffraction of a wave [2 marks - 2023]

• wave passes (through) an aperture or wave passes (by / through / around) an edge

• wave spreads (into geometrical shadow)