The surface of a metal is first illuminated with a light of wavelength 300 nm and later illuminated by another light of wavelength 500 nm . It is observed that the ratio of maximum velocities of photoelectrons in two cases is 3 . The work function of metal value is close to
The ratio of minimum wavelength of Balmer series to maximum wavelength in Brackett series in hydrogen spectrum is
The half-life period of a radioactive element $A$ is 62 years. It decays into another stable element $B$. An archaeologist found a sample in which $A$ and $B$ are in 1:15 ratio. The age of the sample is
The current gain of a transistor in common emitter configuration is 80 . The resistances in collector andbase sides of the circuit are $5 \mathrm{k} \Omega$ and $1 \mathrm{k} \Omega$ respectively. If the input voltage is 2 mV , the output voltage is
4 V
0.4 V
0.8 V
8 V