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15/08/2021 11:02 am
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The values of Planck's constant is 6.63 × 10-34 Js. The velocity of light is 3.0 × 108 m s-1. Which value is closest to the wavelength in nanometres of a quantum of light with frequency of 8 × 1015 s-1?
(a) 5 × 10-18
(b) 4 × 101
(c) 3 × 107
(d) 2 × 10-25
1 Answer
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15/08/2021 11:11 am
Correct answer: (b) 4 × 101
Explanation:
E = hv = \(\frac{ch}{\lambda}\); and v = \(\frac{c}{\lambda}\)
8 x 1015 = \(\frac{3.0 \times 10^8}{\lambda}\)
∴ λ = \(\frac{3.0 \times 10^8}{8 \times 10^{15}}\) = 0.37 x 10-7
= 37.5 x 10-9 m = 40 x 101 m