Question

The wavelength and power of the incident light is 4000 Å and 0.1 W respectively. The number of incident photons is ______.

पर्याय

• 2.011 × 10¹⁷

• 3.011 × 10¹⁷

• 4.011 × 10¹⁷

• 5.011 × 10¹⁷

Answer 1

The wavelength and power of the incident light is 4000 Å and 0.1 W respectively. The number of incident photons is 2.011 × 10¹⁷.

Explanation:

Given: Power (P) = 0.1 W

Wavelength (λ) = 4000 Å

= 4000 × 10⁻¹⁰ m

= 4 × 10⁻⁷ m

Planck’s constant (h) = 6.626 × 10⁻³⁴ J.s

Speed of light (c) = 3 × 10⁸m/s

Formula: P = `n xx E_"photon"`

`P = n xx (hc)/λ`

n =`(P xx λ)/(hc)`

= `(0.1 xx 4 xx 10^-7)/(6.626 xx 10^-34 xx 3 xx 10^8)`

= `(0.4 xx 10^-7)/(19.878 xx 10^-26)`

= 0.02012 × 10¹⁹

= 2.012 × 10¹⁷