1. 1
   A wave machine in a physics lab produces water waves that travel across a tank. A student counts 8 complete waves passing a fixed point every 4.0 s, and measures the distance between 5 successive wave crests as 2.4 m.

   (a)

   What is the frequency of the waves?

   [1 mark]

   • A2.0 Hz
   • B32 Hz
   • C0.5 Hz
   • D4.0 Hz

   (b)

   What is the wavelength of the waves?

   [1 mark]

   • A2.4 m
   • B0.6 m
   • C0.48 m
   • D9.6 m

   (c)

   Calculate the speed of the waves, and state whether these water waves are transverse or longitudinal, giving a reason.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A security mirror (a plane mirror) is mounted on a wall of a shop. A customer stands 3.0 m in front of the mirror, directly facing it.

   (a)

   How far behind the mirror does the customer's image appear to be?

   [1 mark]

   • A0 m
   • B1.5 m
   • C3.0 m
   • D6.0 m

   (b)

   What type of image is formed of the customer by the plane mirror?

   [1 mark]

   • AReal, inverted, diminished
   • BReal, upright, magnified
   • CVirtual, inverted, same size
   • DVirtual, upright, same size

   (c)

   A ray of light from a torch strikes the mirror at an angle of incidence of 35 degrees. State the law of reflection and use it to find the angle of reflection.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A ray of light travelling in air strikes the flat surface of a rectangular glass block at an angle of incidence of 40 degrees, and refracts as it enters the glass, travelling on at an angle of refraction of 25 degrees.

   (a)

   Define refractive index in terms of the ratio of the sines of these angles, and calculate the refractive index of the glass.

   [3 marks]

   (b)

   The same glass has a critical angle. Calculate the critical angle of the glass using your value of refractive index, and describe what happens to a ray of light inside the glass that strikes the glass-air boundary at an angle greater than the critical angle.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An optician is testing two patients. Patient X cannot focus clearly on distant objects (short-sightedness/myopia), and Patient Y cannot focus clearly on nearby objects (long-sightedness/hyperopia).

   (a)

   Using the idea of refraction of light by a lens, explain what causes short-sightedness, and describe the type of lens used to correct it and how this lens corrects the problem.

   [6 marks]

   (b)

   Describe, using the terms principal axis, principal focus and focal length, how a single thin converging lens forms a magnified, upright, virtual image of a nearby object, as used in a magnifying glass, and state one characteristic that distinguishes this virtual image from a real image.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   A construction site worker, standing 660 m from a large flat wall, claps once and hears a clear echo 4.0 s later.

   (a)

   What is the approximate speed of sound in air, based on this echo?

   [1 mark]

   • A330 m/s
   • B165 m/s
   • C660 m/s
   • D2640 m/s

   (b)

   Why must the worker double the distance to the wall when calculating the speed of sound from this echo?

   [1 mark]

   • ABecause sound slows down on the way back
   • BBecause the sound travels to the wall and back again before the echo is heard
   • CBecause the echo is always twice as loud
   • DBecause the speed of sound depends on distance

   (c)

   State the approximate range of frequencies audible to the human ear, and explain, in terms of frequency, why ultrasound used in medical scanning cannot be heard by a person.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   A hospital uses X-rays to image a patient's broken bone, and separately uses gamma rays to sterilise surgical equipment. A security firm uses ultraviolet radiation to reveal hidden security markings on banknotes.

   (a)

   Which of these electromagnetic waves has the shortest wavelength?

   [1 mark]

   • AUltraviolet
   • BInfrared
   • CGamma rays
   • DX-rays

   (b)

   What is a known harmful effect of excessive exposure to X-rays on the human body?

   [1 mark]

   • ASunburn of the skin
   • BHeating of body cells
   • CDamage to the retina of the eye
   • DMutation or damage to cells in the body

   (c)

   State the speed of electromagnetic waves in a vacuum, and state one similarity between how gamma rays and radio waves travel through a vacuum.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   A lighting designer hangs a triangular glass prism ornament in a shop window. Sunlight (white light) passes through the prism and produces a spread-out pattern of coloured light on the wall of the shop, with the colours arranged in a continuous band.

   (a)

   State the name given to this spreading of white light into a band of colours, and list the traditional seven colours of the visible spectrum in order, starting with the colour that is refracted least by the prism.

   [3 marks]

   (b)

   Explain, in terms of the different colours travelling at different speeds inside the glass, why the prism separates white light into this band of colours, and state what is meant by describing a beam of light as monochromatic.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   A fishing trawler's echo sounder sends a pulse of ultrasound straight down towards the seabed. The pulse travels through seawater, in which sound travels at a speed of 1500 m/s, and the reflected pulse (echo) returns to the trawler's detector 0.080 s after it was sent.

   (a)

   Define ultrasound, calculate the depth of water beneath the trawler, and describe, in terms of compressions and rarefactions, the nature of the sound wave travelling through the water.

   [6 marks]

   (b)

   Explain why the trawler's crew choose to use ultrasound rather than audible sound for this echo-sounding system, and describe one other practical use of ultrasound, explaining what property of the reflected ultrasound pulses makes this use possible.

   [6 marks]

   Total for question 8: 12 marks

End of questions