If the momentum of a photon is $p$,then its frequency is ........

$A$ light bulb emits $5\%$ of its energy as visible light. How many quanta are emitted per second by a $100 \ W$ lamp? (Assume the wavelength of visible light is $5.6 \times 10^{-5} \ cm$)

Write the equation for the energy of a photon.

$A$ stick of $1 \, m$ is moving with a velocity of $2.7 \times 10^8 \, m/s$. What is the apparent length of the stick in meters? (Given: $c = 3 \times 10^8 \, m/s$)

$A$ lamp of power $942 \ W$ radiates energy uniformly in all directions. The wavelength of radiation is $660 \ nm$. The photon flux on a small screen $5.0 \ m$ from the lamp in units of $\frac{\text{photon}}{m^2 \cdot s}$ is (Take Planck's constant $h = 6.6 \times 10^{-34} \ J \cdot s$ and speed of light $c = 3 \times 10^8 \ m/s$)

The photoelectric effect can be understood on the basis of