One milliwatt of light of wavelength 4560 ma | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) The power of incident light $P = 1 \ mW = 10^{-3} \ W$. The wavelength $\lambda = 4560 \ \mathring{A} = 4560 	imes 10^{-10} \ m$. First,calculate

Vedclass · Accepted Answer

$1.856 	imes 10^{-6} \ A$

Vedclass · Answer

(A) The power of incident light $P = 1 \ mW = 10^{-3} \ W$. The wavelength $\lambda = 4560 \ \mathring{A} = 4560 	imes 10^{-10} \ m$. First,calculate the number of photons incident per second $(n_p)$: $n_p = \frac{P}{E_{photon}} = \frac{P \lambda}{hc} = \frac{10^{-3} 	imes 4560 	imes 10^{-10}}{6.62 	imes 10^{-34} 	imes 3 	imes 10^8} \approx 2.295 	imes 10^{15} 	ext{ photons/s}$. The number of photoelectrons emitted per second $(n_e)$ is given by the quantum efficiency $\eta = 0.5\% = 0.005$: $n_e = \eta 	imes n_p = 0.005 	imes 2.295 	imes 10^{15} \approx 1.1475 	imes 10^{13} 	ext{ electrons/s}$. The photoelectric current $I_p$ is given by $I_p = n_e 	imes e$,where $e = 1.6 	imes 10^{-19} \ C$: $I_p = 1.1475 	imes 10^{13} 	imes 1.6 	imes 10^{-19} \approx 1.836 	imes 10^{-6} \ A$. Rounding to the provided option,the correct value is $1.856 	imes 10^{-6} \ A$.

Similar Questions

Threshold frequency for a metal is $15 \times 10^{14} \, Hz$. The light of wavelength $6000 \, \text{Å}$ falls on the metal surface. Then photoelectrons [velocity of light in air, $c = 3 \times 10^8 \, m/s$]:

Which figure shows the correct variation of applied potential difference $(V)$ with photoelectric current $(I)$ at two different intensities of light $(I_1 < I_2)$ of the same wavelength?

Light of frequency $1.5 \nu_0$ (where $\nu_0$ is the threshold frequency) is incident on a photosensitive material. If the frequency is halved and the intensity is doubled,what happens to the photocurrent?

Which one of the following is true in photoelectric emission?

The figure shows the variation of photocurrent with anode potential for four different radiations. Let $I_a, I_b, I_c$ and $I_d$ be the intensities for the curves $a, b, c$ and $d$ respectively $[f_a, f_b, f_c$ and $f_d$ are frequencies respectively].

Vedclass Test Series

Exam Paper Generator

Online Exam Module