Question

The value of Planck's constant is 6.63 × 10^-34 Js. The velocity of light is 3.0 × 10⁸ ms^-1. Which value is closest to the wavelength in nanometers of a quantum of light with frequency of 8 × 10¹⁵ s^-1?

(a) 5 × 10¹⁸

(b) 4 × 10¹

(c) 3 × 10⁷

(d) 2 × 10^-25

Answer 1

Correct option is (b) 4 × 10¹

\(\lambda = \frac cv\)

\(= \frac{3 \times 10^8}{8 \times 10^{15}}\)

\(= 3.75 \times 10^{-8}\)

\(= 3.75 \times 10^{-8} \times 10^9\) nm

\(= 4 \times 10^1\) nm