Practise Types of electromagnetic waves. 11 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
A radio station broadcasts using radio waves with a frequency of 97.5 MHz. The speed of electromagnetic waves in air is 3.0 × 108 m/s.
(a) Calculate the wavelength of the radio waves.[3]
(b) Give two examples of electromagnetic waves transferring energy from a source to an absorber.[2]
(c) Human eyes can only detect a limited range of electromagnetic waves. Name this part of the electromagnetic spectrum.[1]
Show the answer and mark scheme
(a)Answer: 3.1 m (3.08 m) m
97.5 MHz = 9.75 × 107 Hz
λ = 3.0 × 108 ÷ 9.75 × 107
3.1 (m)
(b)Answer: Any two, e.g. the Sun warming your skin; a microwave oven heating food.
infrared / visible light from the Sun warming the Earth or a person's skin
microwaves from a microwave oven heating food
radio waves from a transmitter being absorbed by an aerial
infrared from an electric heater warming a room
light from a lamp being absorbed by a solar cell / the eye
(c)Answer: Visible light
visible light
Question 3Hard8 marks
The speed of electromagnetic waves in a vacuum is 3.0 × 108 m/s.
(a) An X-ray used in a hospital has a wavelength of 1.2 × 10−10 m. Calculate the frequency of the X-ray.[3]
(b) The wavelengths of visible light range from about 4.0 × 10−7 m (violet) to 7.0 × 10−7 m (red). Calculate the range of frequencies of visible light. Give your answers to 2 significant figures.[3]
(c) Calculate how many times greater the frequency of the X-ray is than the frequency of red light.[2]