In a parallel plate air capacitor the distance between plates is reduced to one fourth and the space between them is filled with a dielectric medium of constant 2 . If the initial capacity of the capacitor is $4 \mu \mathrm{~F}$. then its new capacity is

An aircraft is moving with uniform velocity $150 \mathrm{~m} / \mathrm{s}$ in the space. If all the forces acting on it are balanced, then it will

In case of $p$-n junction diode, the width of depletion region is

In the study of transistor as an amplifier, the ratio of collector current to emitter current is 0.98 then the ratio of collector current to base current will be