The energy of a photon is calculated by ......

In a $H$ atom,if the angular momentum of an electron is $3.164 \times 10^{-34} \ kg \ m^2 \ s^{-1}$,what is the energy of the electron in that orbit in $eV$?

The postulate of Bohr theory that electrons jump from one orbit to the other,rather than flow,is according to:

The frequency and energy of a photon with a wavelength of $4000 \ \mathring{A}$ are respectively.......

Calculate the energy of an electron in the first four orbits of a hydrogen atom in $kJ \, mol^{-1}$ (Given: $N_A = 6.02 \times 10^{23} \, mol^{-1}$,Rydberg constant $R_H = 2.18 \times 10^{-18} \, J$).

Which of the following statements are correct,if the threshold frequency of caesium is $5.16 \times 10^{14} \ Hz$?
$A.$ When $Cs$ is placed inside a vacuum chamber with an ammeter connected to it and yellow light is focused on $Cs$,the ammeter shows the presence of current.
$B.$ When the brightness of the yellow light is dimmed,the value of the current in the ammeter is reduced.
$C.$ When a red light is used instead of the yellow light,the current produced is higher with respect to the yellow light.
$D.$ When a blue light is used,the ammeter shows the formation of current.
$E.$ When a white light is used,the ammeter shows the formation of current.
Choose the correct answer from the options given below: