Worksheet 14.1

Worksheet 14.1 Waves: speed, frequency and wavelength Practise using the equation that links the speed, frequency and wavelength of a wave. Notes There are many types of wave. For each type, wave speed, frequency and wavelength are related by this equation: wave speed = frequency × wavelength Questions 1 A student observes some ripples in a ripple tank. She notes that 20 waves occupy a distance of 4.8 cm. What is their wavelength? 2 Calculate the speed of sound in air if a sound of frequency 220 Hz has a wavelength of 1.50 m. 3 Sound has a speed of 1500 m/s in water. Calculate the wavelength of sound waves of frequency 480 Hz in water. 4 When ripples travel into shallower water, their wavelength decreases. Their frequency remains constant. a Does their speed increase, decrease or stay the same? When light waves travel from air into glass, their speed decreases. Their frequency remains constant. b Does their wavelength increase, decrease or stay the same? c How do light waves change when they travel from glass into air? 5 Red light of wavelength 6.50 × 10−7 m travels through air, where its speed is 3.0 × 108 m/s. a What is its frequency? b What will its wavelength become in glass, where its speed is 2.1 × 108 m/s? 6 Ultrasound waves are sometimes used to clean small items of jewellery, which are immersed in water and subjected to ultrasound. What is the wavelength of ultrasound waves of frequency 40 kHz in water? Give your answer in cm. (Speed of ultrasound in water = 1500 m/s.)

© Cambridge University Press 2014 IGCSE® Physics

Worksheet 14.1

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