Print all · Topic 3

Waves — all three papers

Pearson Edexcel International GCSE

Physics — Topic 3 Paper 1

Waves · specification 3.1–3.23

Time allowed: 30 minutes

Total marks: 25

Candidate name:

Centre / class:

Answer all questions. You may use a calculator. Show your working. Take the speed of electromagnetic waves in free space as $3.0 \times 10^8\,\text{m/s}$.

1

A student watches ripples on a pond. The frequency of the ripples is $2.5\,\text{Hz}$ and the wavelength is $12\,\text{cm}$.

(a) State whether water ripples are transverse or longitudinal. Explain your answer.

[2]

(b) Calculate the speed of the ripples.

[3]

(c) State the time period of the ripples.

[1]

(Total for Question 1 = 6 marks)

2

A ray of light in air hits a rectangular glass block. The angle of incidence is $42^\circ$ and the angle of refraction in the glass is $26^\circ$.

(a) State the law of reflection.

[1]

(b) Calculate the refractive index of the glass.

[3]

(c) Another sample of glass has $n=1.50$. Calculate the critical angle for a glass–air boundary.

[3]

(Total for Question 2 = 7 marks)

3

Ultraviolet radiation is part of the electromagnetic spectrum. A dentist uses an optical fibre to send visible light into a patient’s mouth.

(a) Name the EM band with a longer wavelength than ultraviolet and the band with a shorter wavelength than ultraviolet, using neighbours in the spectrum.

[2]

(b) Explain how total internal reflection allows light to travel along the optical fibre.

[2]

(c) State one detrimental effect of excessive ultraviolet exposure and one protective measure.

[2]

(Total for Question 3 = 6 marks)

4

A student investigates the refractive index of a rectangular glass block.

(a) Describe a method the student should use to obtain values of $i$ and $r$. Include how the student draws the normal.

[4]

(b) Suggest two ways the student could reduce the uncertainty in $n$.

[2]

(Total for Question 4 = 6 marks)

END OF PAPER 1

Pearson Edexcel International GCSE

Physics — Topic 3 Paper 2

Waves · specification 3.1–3.23

Time allowed: 30 minutes

Total marks: 25

Candidate name:

Centre / class:

Answer all questions. You may use a calculator. Show your working. Take the speed of electromagnetic waves in free space as $3.0 \times 10^8\,\text{m/s}$.

1

A radio mast broadcasts at a frequency of $150\,\text{MHz}$.

(a) Explain the difference between a transverse wave and a longitudinal wave. State which type a radio wave is.

[3]

(b) Calculate the wavelength of the radio wave in air.

[3]

(Total for Question 1 = 6 marks)

2

A student sends a ray of light from air into a perspex block. $i=35^\circ$ and $r=22^\circ$.

(a) On a ray diagram, from which line should $i$ and $r$ be measured?

[1]

(b) Calculate the refractive index of the perspex.

[3]

(c) For perspex, $n=1.49$. Calculate the critical angle at a perspex–air boundary.

[3]

(Total for Question 2 = 7 marks)

3

Microwaves are used for satellite transmissions. Visible light can be sent along an optical fibre.

(a) State one other specification use of microwaves.

[1]

(b) State the two conditions for total internal reflection in the fibre.

[2]

(c) Explain one hazard of excessive microwave exposure and how a person can be protected.

[3]

(Total for Question 3 = 6 marks)

4

The same student measures $n$ for the perspex block using a ray box.

(a) Describe how the student should mark the path of the ray through the block after the block is removed.

[3]

(b) The student uses only $i=8^\circ$. Explain why this is a poor choice, and state one improvement.

[3]

(Total for Question 4 = 6 marks)

END OF PAPER 2

Pearson Edexcel International GCSE

Physics — Topic 3 Paper 3

Waves · specification 3.1–3.23

Time allowed: 30 minutes

Total marks: 25

Candidate name:

Centre / class:

Answer all questions. You may use a calculator. Show your working. Take the speed of sound in air as $340\,\text{m/s}$.

1

A loudspeaker at a swimming pool produces a note of frequency $680\,\text{Hz}$.

(a) Sound is a longitudinal wave. Describe what this means, and name the two regions that repeat along a sound wave.

[3]

(b) Calculate the wavelength of the sound in air.

[2]

(c) A swimmer moves towards the loudspeaker. State what happens to the frequency she hears. Name the effect.

[1]

(Total for Question 1 = 6 marks)

2

A ray of light in air hits the surface of the pool. $i=50^\circ$ and $r=31^\circ$.

(a) State whether the light speeds up or slows down as it enters the water, and whether it bends towards or away from the normal.

[2]

(b) Calculate the refractive index of the water.

[2]

(c) Take $n=1.33$ for water. Calculate the critical angle for a water–air boundary.

[3]

(Total for Question 2 = 7 marks)

3

X-rays are used to check a swimmer’s broken wrist. A 45° glass prism can turn a light ray through $90^\circ$ by total internal reflection.

(a) State one specification use of X-rays other than medical imaging.

[1]

(b) Explain why a 45° prism can use TIR if glass has $c \approx 42^\circ$.

[2]

(c) Gamma rays are used to sterilise medical equipment. State one detrimental effect of gamma rays and one protective measure.

[3]

(Total for Question 3 = 6 marks)

4

A student measures $i$ and $r$ for a glass block.

$i$ / ° 20 30 40 50
$r$ / ° 13 19 25 40

(a) Calculate $n$ using the $40^\circ$ pair of results.

[2]

(b) Identify the anomalous pair and suggest one practical reason for it.

[2]

(c) State how the student should use the remaining results to give a better value of $n$.

[2]

(Total for Question 4 = 6 marks)

END OF PAPER 3