The minimum intensity of light to be detected | vedclass

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

Question

(C) The intensity $I$ is defined as power per unit area: $I = \frac{P}{A}$.Given $I = 10^{-10} \ W/m^2$ and $A = 10^{-6} \ m^2$,the power $P$ entering

Vedclass · Accepted Answer

$300$

Vedclass · Answer

(C) The intensity $I$ is defined as power per unit area: $I = \frac{P}{A}$.Given $I = 10^{-10} \ W/m^2$ and $A = 10^{-6} \ m^2$,the power $P$ entering the eye is $P = I 	imes A = 10^{-10} 	imes 10^{-6} = 10^{-16} \ W$.The power of a beam of $n$ photons per second is given by $P = \frac{n \cdot h \cdot c}{\lambda}$.Rearranging for the number of photons per second $\frac{n}{t} = \frac{P \cdot \lambda}{h \cdot c}$.Substituting the values: $\frac{n}{t} = \frac{10^{-16} 	imes 5.6 	imes 10^{-7}}{6.63 	imes 10^{-34} 	imes 3 	imes 10^8}$.$\frac{n}{t} = \frac{5.6 	imes 10^{-23}}{19.89 	imes 10^{-26}} \approx 281.5 \approx 300$ photons per second.

The minimum intensity of light to be detected by the human eye is $10^{-10} \ W/m^2$. The number of photons of wavelength $5.6 \times 10^{-7} \ m$ entering the eye,with a pupil area of $10^{-6} \ m^2$,per second for vision will be nearly:

Similar Questions

If the energy of a photon with wavelength $6000 \ \mathring{A}$ is $3.32 \times 10^{-19} \ J$, then the energy of a photon with wavelength $4000 \ \mathring{A}$ is ............. $eV$.

In the Compton scattering process,the incident $X$-radiation is scattered at an angle of $60^{\circ}$. The wavelength of the scattered radiation is $0.22 \ \text{Å}$. The wavelength of the incident $X$-radiation in $\text{Å}$ units is:

The energy of a photon with a wavelength of $\lambda = 4000 \ \mathring{A}$ is equal to ... $eV$.

What is the energy and momentum of a photon having frequency $v$?

$A$ radio station broadcasts at a wavelength of $300 \ m$. If the radiating power of the transmitter is $10 \ kW$,then the number of photons emitted per second is:

Vedclass Test Series

Exam Paper Generator

Online Exam Module