List of top Physics Questions on Photoelectric Effect asked in IIT JAM BT

In 2 N H\(_2\)SO\(_4\), an organic compound shows fluorescence with quantum yield $\phi_f = 0.42$ and fluorescence rate constant $k_f = 5.25 \times 10^{7}\ \text{s}^{-1}$. The observed fluorescence lifetime (correct to 1 decimal place) is ............ ns.
Two sources P and Q produce electromagnetic waves of wavelengths $\lambda$ and $2\lambda$, respectively. Source P ejects a photon with maximum kinetic energy 4.0 eV from a metal with work function 2.0 eV. The maximum kinetic energy (eV) of a photon ejected by source Q from the same metal is .............