4 Waves Exam-style questions. AQA Physics. 1 a Define the amplitude of a wave. (1 mark) b i

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1 1 a Define the amplitude of a wave. b i Other than electromagnetic radiation, give one example of a wave that is transverse. ii State one difference between a transverse wave and a longitudinal wave. c Figure 1 shows two identical polarising filters, A and B, and an unpolarised light source. The arrows indicate the plane in which the electric field of the wave oscillates. i If polarised light is reaching the observer, draw the direction of the transmission axis on filter B in Figure 1. Figure 1 ii The polarising filter B is rotated clockwise through 360 about line XY from the position shown in Figure 2. On the axes below, sketch how the light intensity reaching the observer varies as this is done. Figure 2 This resource sheet may have been changed from the original 1

2 d State one application, other than in education, of a polarising filter and give a reason for its use. From AQA Physics A PHYA2 Mechanics, Materials and Waves June 2010 (Question 3) This resource sheet may have been changed from the original 2

3 2 Ultrasound waves are used to produce images of a foetus inside a womb. a Explain what is meant by the frequency of a wave. b Ultrasound is a longitudinal wave. Describe the nature of a longitudinal wave. c To produce an image with sufficient detail, the wavelength of the ultrasound must be 0.50 mm. The speed of the ultrasound in body tissue is 1540 m s 1. Calculate the frequency of the ultrasound at this wavelength. Give your answer to an appropriate number of significant figures. frequency From AQA Physics A PHYA2 Mechanics, Materials and Waves June 2014 (Question 7) Hz This resource sheet may have been changed from the original 3

4 3 Figure 3a shows a side view of a string on a guitar. The string cannot move at either of the two bridges when it is vibrating. When vibrating at its first harmonic, the frequency of the sound produced is 108 Hz. a i On Figure 3a, sketch the stationary wave produced when the string is vibrating at its first harmonic. ii Figure 3a Calculate the wavelength of the first harmonic mode of vibration. iii Calculate the speed of a progressive wave on this string. m m s 1 b While tuning the guitar, the guitarist produces a harmonic that has a node 0.16 m from bridge A. i On Figure 3b, sketch the stationary wave produced and label all nodes that are present. Figure 3b This resource sheet may have been changed from the original 4

5 ii Calculate the frequency of the harmonic. c The guitarist needs to raise the first harmonic frequency of vibration of this string. State one way in which this can be achieved. Hz From AQA Physics A PHYA2 Mechanics, Materials and Waves January 2010 (Question 4) This resource sheet may have been changed from the original 5

6 4 Figure 4 shows two ways in which a wave can travel along a slinky spring. Figure 4 a State and explain which wave is longitudinal. b On Figure 4, i clearly indicate and label the wavelength of wave B ii use arrows to show the direction in which the points P and Q are about to move as each wave moves to the right. c Electromagnetic waves are similar in nature to wave A. Explain why it is important to align the aerial of a television correctly to receive the strongest signal. From AQA Physics A PHYA2 Mechanics, Materials and Waves June 2012 (Question 7) This resource sheet may have been changed from the original 6

7 5 When a note is played on a violin, the sound it produces consists of the first harmonic and many higher harmonics. Figure 5a shows the shape of the string for a stationary wave that corresponds to one of these higher harmonics. The positions of maximum and zero displacement for one harmonic are shown. Points A and B are fixed. Points X, Y, and Z are points on the string. Figure 5a a i Describe the motion of point X. ii State the phase relationship between X and Y X and Z b The frequency of this harmonic is 780 Hz. i Show that the speed of a progressive wave on this string is about 125 m s 1. ii Calculate the time taken for the string at point Z to move from maximum displacement back to zero displacement. s (3 marks) This resource sheet may have been changed from the original 7

8 c The violinist presses on the string at C to shorten the part of the string that vibrates. Figure 5b shows the string between C and B vibrating at its first harmonic. The length of the whole string is 320 mm and the distance between C and B is 240 mm. Figure 5b i State the name given to the point on the wave midway between C and B. ii Calculate the wavelength of this stationary wave. iii Calculate the frequency of this first harmonic. The speed of the progressive wave remains at 125 m s 1. m Hz From AQA Physics A PHYA2 Mechanics, Materials and Waves June 2012 (Question 6) This resource sheet may have been changed from the original 8