The energy of a photon with a wavelength of $450 \, nm$ is ............

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

Our eye can detect $5 \times 10^4$ photons per second per square meter of green light $(\lambda = 5000 \ \mathring{A})$. If the ear can detect $10^{-13} \ W/m^2$,how many times more sensitive is the eye compared to the ear?

The rest mass energy of an electron is $0.54 \, MeV$. If the velocity of the electron is $0.8 \, c$,then the kinetic energy $(K.E.)$ of the electron is .......... $MeV$.

In an accelerator experiment on high-energy collisions of electrons with positrons,a certain event is interpreted as annihilation of an electron-positron pair of total energy $10.2 \; BeV$ into two $\gamma$-rays of equal energy. What is the wavelength associated with each $\gamma$-ray? $(1 \; BeV = 10^9 \; eV)$

According to the photon theory of light,which of the following physical quantities associated with a photon does not change as it collides with an electron in a vacuum?