22 12 Kathy and Jonathan collect information about different electromagnetic waves. Type of electromagnetic wave
Wave speed in m/s
Wavelength in m
microwave
3 × 108
2 × 10–2
radio
3 × 108
2
X-ray
3 × 108
2 × 10–9
infrared
3 × 108
2 × 10–5
(a) Use the information in the table to calculate the frequency of the microwave. ................................................................................................................................................... ................................................................................................................................................... frequency = .................................................... Hz [3] (b) The energy of electromagnetic waves is carried by photons. The chart shows information about frequency and photon energy. frequency in Hz
106 107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020
photon energy in arbitrary units 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 (i)
1
101 102 103 104 105 106
Use the chart to describe the relationship between frequency and energy. ........................................................................................................................................... ...................................................................................................................................... [1]
(ii)
Infrared waves can vary in wavelength. Infrared radiation from source A has a wavelength of 1 × 10–5 m. Infrared radiation from source B has a wavelength of 1 × 10–6 m. Compare the energy and potential dangers to humans of the radiation emitted by sources A and B. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] [Total: 6]
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