1. 1
   A radio station broadcasts a signal with a frequency of 100 000 Hz and a wavelength of 3000 m, travelling through air.

   (a)

   Which equation should be used to calculate the speed of this radio wave?

   [1 mark]

   • Awave speed = frequency × wavelength
   • Bwave speed = frequency ÷ wavelength
   • Cwave speed = frequency + wavelength
   • Dwave speed = wavelength ÷ frequency

   (b)

   Which other type of electromagnetic wave is commonly used for satellite communication?

   [1 mark]

   • AGamma rays
   • BMicrowaves
   • CUltraviolet
   • DX-rays

   (c)

   Calculate the speed of this radio wave.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A ray of light travelling through air strikes the flat surface of a still pond at an angle of incidence of 40°, and refracts into the water below, where the angle of refraction is 29°.

   (a)

   Which equation is used to calculate the refractive index of the water from the two angles given?

   [1 mark]

   • An = sin r ÷ sin i
   • Bn = sin i + sin r
   • Cn = sin i ÷ sin r
   • Dn = sin r × sin i

   (b)

   As the light ray passes from air into the denser water, how does it bend relative to the normal?

   [1 mark]

   • AAway from the normal
   • BIt does not bend
   • CParallel to the normal
   • DTowards the normal

   (c)

   Calculate the refractive index of the water, giving your answer to 3 significant figures.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A ship's sonar emits a sound pulse that travels through seawater at a speed of 1500 m/s. The pulse reflects off the seabed directly below and returns to the ship's receiver 4 s after it was emitted.

   (a)

   Calculate the depth of the seabed below the ship.

   [3 marks]

   (b)

   The dominant frequency of the sonar pulse is 50 000 Hz. State whether this frequency is within the range of human hearing, and calculate the wavelength of the pulse in seawater.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A ray of light inside a glass optical component (refractive index 1.5) travels towards a flat glass-air boundary and strikes it at an angle of 50° to the normal. The light has a frequency of 5 × 10¹⁴ Hz and travels at 2 × 10⁸ m/s in the glass.

   (a)

   Calculate the critical angle for this glass, and determine whether the ray undergoes total internal reflection or refracts out of the glass at this boundary, given it strikes the boundary at 50° to the normal.

   [6 marks]

   (b)

   The ray eventually leaves the glass through a different face, entering air (speed 3 × 10⁸ m/s). Explain what happens to its frequency, wavelength and speed as it crosses from glass into air, and calculate its wavelength in air.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   A wireless router transmits a radio signal with a wavelength of 0.125 m. The signal travels through air at the speed of light, 3 × 10⁸ m/s.

   (a)

   Calculate the frequency of the router's radio signal.

   [1 mark]

   • A2.4 × 10⁸ Hz
   • B2.4 × 10⁹ Hz
   • C3.75 × 10⁹ Hz
   • D24 × 10⁹ Hz

   (b)

   Which property is shared by all electromagnetic waves travelling through a vacuum?

   [1 mark]

   • AThey all travel at the same speed
   • BThey all have the same wavelength
   • CThey all have the same frequency
   • DThey can all be detected by the human eye

   (c)

   Using a frequency of 2.4 × 10⁹ Hz for this signal, calculate its time period.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   A student directs a ray of light at a plane mirror so that it strikes the mirror's surface at an angle of 35° to the mirror's surface itself, rather than to the normal.

   (a)

   What is the angle of reflection of the ray from the mirror?

   [1 mark]

   • A35°
   • B45°
   • C20°
   • D55°

   (b)

   Which law governs the relationship between the incident ray and the reflected ray at the mirror?

   [1 mark]

   • AThe angle of incidence is always 90°
   • BThe angle of reflection is always half the angle of incidence
   • CThe angle of incidence equals the angle of reflection
   • DThe angle of incidence equals twice the angle of reflection

   (c)

   The mirror is now rotated so that the ray strikes it at 25° to the normal instead. Calculate the new angle of reflection.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   A guitarist plucks a string, which vibrates at a frequency of 440 Hz, producing a sound wave that is picked up by a microphone connected to a data logger.

   (a)

   Calculate the period of the sound wave produced when the string vibrates at 440 Hz.

   [3 marks]

   (b)

   The guitarist then plucks the string harder, without changing its length or tension. Explain the effect this has on the sound wave produced, in terms of amplitude and loudness, and state whether the frequency and pitch of the note change.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   A hiker shouts towards a distant canyon wall and hears an echo 1.5 s later. The speed of sound in air is 340 m/s. The dominant frequency of the hiker's shout is 200 Hz.

   (a)

   Calculate the distance from the hiker to the canyon wall, explaining how the 1.5 s time is used in your calculation.

   [6 marks]

   (b)

   Calculate the wavelength of the hiker's shout in air, and explain two ways in which this sound wave differs from an electromagnetic wave of the same frequency.

   [6 marks]

   Total for question 8: 12 marks

End of questions