What is the maximum wavelength of the line of Balmer series of hydrogen spectrum ($\mathrm{R} =$$1.09\times {10}^7 {\mathrm{m}}^{-1}$ )
 

In the second orbit of $\mathrm{H}$$-$atom what is the velocity of ${\mathrm{e}}^{-}$?

When on metal sheet fall ${\mathrm{\lambda }}_1$ light will eject electron with ${\mathrm{V}}_1$ velocity and with ${\mathrm{\lambda }}_2$ light eject electron of ${\mathrm{V}}_2$ velocity. What is ${\mathrm{V}}_2^2-{\mathrm{V}}_1^2$ value?

The energy of a photon is $3.03\times {10}^{-19} \mathrm{J}$, then the wavelength of this photon is

(Given, $\mathrm{h}=6.63\times {10}^{-34} \mathrm{J} \mathrm{s}, \mathrm{c}=3.00\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1}$)