The eye can detect  $5 ×10^4$ photons per square metre per sec of green light ($\lambda$ $= 5000\ \mathop A\limits^o $) while the ear can detect ${10^{ – 13}}\,(W/{m^2})$. The factor by which the eye is more sensitive as a power detector than the ear is close to

Write characteristic of photon or How photon of electromagnetic radiation can be represented ? 

A photon of $1.7 \times {10^{ – 13}}$ Joules is absorbed by a material under special circumstances. The correct statement is

A photon falls through a height of $1 \,km$ through the earth's gravitational field. To calculate the change in its frequency, take its mass to be $h v / c^{2}$. The fractional change in frequency $v$ is close to

A pulse of light of duration $100 \ ns$ is absorbed completely by a small object initially at rest. Power of the pulse is $30 \ mV$ and the speed of light is $3 \times 10 ^8\ ms ^{-1}$. The final momentum of the object is :