The shortest wavelength in Lyman series is $912 \mathop {\rm{A}}\limits^{\rm{o}}$. Then, the longest wavelength in the series must be

Half-life of radioactive sample is 24 h . If a newly prepared radioactive sample shows 4 times the allowed and safe value of radio activity, the minimum time after which one can work safely with the source is

The current gain of a transistor is 0.98 . If the transistor is used in a common emitter arrangement what would be the change in collector current corresponding to a change of 0.5 mA in the base current?

In a $p-n-p$ transistor, the current carriers are