There are ${n_1}$ photons of frequency ${\gamma _1}$ in a beam of light. In an equally energetic beam, there are ${n_2}$ photons of frequency ${\gamma _2}$. Then the correct relation is
$\frac{{{n_1}}}{{{n_2}}} = 1$
$\frac{{{n_1}}}{{{n_2}}} = \frac{{{\gamma _1}}}{{{\gamma _2}}}$
$\frac{{{n_1}}}{{{n_2}}} = \frac{{{\gamma _2}}}{{{\gamma _1}}}$
$\frac{{{n_1}}}{{{n_2}}} = \frac{{\gamma _1^2}}{{\gamma _2^2}}$
Which of the following statement is not correct
A convex lens of focal length $40 \mathrm{~cm}$ forms an image of an extended source of light on a photoelectric cell. A current I is produced. The lens is replaced by another convex lens having the same diameter but focal length $20 \mathrm{~cm}$. The photoelectric current now is:
Write equation of energy of photon.
The force on a hemisphere of radius $1\, cm$ if a parallel beam of monochromatic light of wavelength $500\, nm$. falls on it with an intensity of $0.5\, W/cm^2$, striking the curved surface in a direction which is perpendicular to the flat face of the hemisphere is (assume the collisions to be perfectly inelastic)
Two sources of light emit with a power of $200 \mathrm{~W}$. The ratio of number of photons of visible light emitted by each source having wavelengths $300\ \mathrm{nm}$ and $500 \mathrm{~nm}$ respectively, will be :