Edexcel A-Level Physics AS 2.3 Waves and Particle Nature of Light Questions

Practise Edexcel A-Level Physics waves and particle nature of light through stationary waves, refraction, diffraction, photons, spectra and photoelectric calculations.

Exam points

analyse stationary waves using nodes, antinodes, superposition and string-frequency graphs
apply refraction, critical-angle and optical-fibre ideas to ray paths and pulse spreading
use photon energy, de Broglie wavelength and energy levels in photoelectric questions

Covered syllabus points

2.3.33 - Wave quantities 2.3.34 - Wave equation 2.3.35 - Longitudinal waves 2.3.36 - Transverse waves 2.3.37 - Wave graphs 2.3.38 - Core Practical 4 - speed of sound in air 2.3.39 - Wavefronts, coherence and interference 2.3.40 - Phase difference and path difference 2.3.41 - Standing waves, nodes and antinodes 2.3.42 - Speed of a transverse wave on a string 2.3.43 - Core Practical 5 - vibrating string frequency 2.3.44 - Intensity of radiation 2.3.45 - Refraction at a boundary 2.3.46 - Critical angle 2.3.47 - Total internal reflection 2.3.48 - Measuring refractive index 2.3.49 - Plane polarisation 2.3.50 - Diffraction and Huygens’ construction 2.3.51 - Diffraction grating equation 2.3.52 - Core Practical 6 - wavelength using diffraction grating 2.3.53 - Electron diffraction evidence 2.3.54 - De Broglie wavelength 2.3.55 - Transmission and reflection at boundaries 2.3.56 - Pulse-echo techniques 2.3.57 - Wave and photon models of EM radiation 2.3.58 - Photon energy 2.3.59 - Photon absorption and photoelectron emission 2.3.60 - Threshold frequency and work function 2.3.61 - Electronvolt 2.3.62 - Photoelectric effect evidence 2.3.63 - Atomic line spectra and energy levels

[Maximum number: 1]

The time period of a wave decreases.
Which of the following properties of the wave increases?

amplitude

frequency

speed

wavelength

[Maximum number: 8]

A student investigated the reflection of microwaves from a metal plate and a glass plate. The metal plate reflects microwaves and the glass plate partially reflects microwaves.

A plan view of the apparatus is shown.

The metal plate, the transmitter and the receiver were kept in fixed positions. The value of d was varied by moving the glass plate.

Figure for Question 2 — Edexcel A-Level Physics AS

(a)

As d varied, the intensity of the microwaves detected by the receiver varied.

Explain why.

[ 3 ]

(b)

The student recorded values of d when the receiver showed a maximum value of intensity.

He recorded d for a sequence of five maxima.

Maxima | 1 | 2 | 3 | 4 | 5
d / cm | 9.9 | 11.1 | 12.7 | 13.9 | 15.4

Figure for Question (b) — Edexcel A-Level Physics AS

[ 5 ]

(i)

Determine the wavelength of the microwaves being transmitted.

Wavelength =

[ 3 ]

(ii)

Calculate the frequency of the microwaves being transmitted.

Frequency =

Figure for Question (ii) — Edexcel A-Level Physics AS

[ 2 ]

[Maximum number: 12]

The photograph shows a musical instrument called a violin.

Figure for Question 3 — Edexcel A-Level Physics AS

The violin has four strings. Each string is held in a fixed position by a peg and at the bridge.

When a string is plucked, a stationary wave forms on the string.

(a)

Explain how a stationary wave forms on the string.
(3)

[ 3 ]

(b)

The simplest stationary wave has a node at each end and an antinode at the centre. Its frequency is the fundamental frequency.

String	Fundamental frequency / Hz
1	196
2	294
3	440
4	659

The tension is $71.5\,\mathrm{N}$ , length $0.32\,\mathrm{m}$ , and mass per unit length $2.03\times10^{-3}\,\mathrm{kg\,m^{-1}}$ . Deduce which string it is.

[ 4 ]

The wave speed is $v=\sqrt{\frac{T}{\mu}}=\sqrt{\frac{71.5}{2.03\times10^{-3}}}=187.7\,\mathrm{m\,s^{-1}}.$ For the fundamental, $\lambda=2L=0.64\,\mathrm{m}$ , so $f=v/\lambda=293\,\mathrm{Hz}$ , closest to string 2.

(c)

The stationary wave on the string causes sound waves to be transmitted through the air.

Describe the similarities and differences between the stationary wave on the string and the sound waves transmitted through the air.

[ 5 ]

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Covered syllabus points

Question 1

Question 2

Question (a)

Question (b)

Question (i)

Question (ii)

Question 3

Question (a)

Question (b)

Question (c)