A body of mass 'M' and radius 'R', situated on the surface of the earth becomes weightless at its equator when the rotational kinetic energy of the earth reaches a critical value 'K'. The value of 'K' is given by [Assume the earth as a solid sphere, g = gravitational acceleration on the earth's surfacde]
A circuit has self-inductance 'L' H and carries a current 'I' A. To prevent sparking when the circuit is switched off, a capacitor which can withstand 'V' volt is used. The least capacitance of the capacitor connected across the switch must be equal to
A straight wire of diameter $$0.4 \mathrm{~mm}$$ carrying a current of $$2 \mathrm{~A}$$ is replaced by another wire of 0.8 $$\mathrm{mm}$$ diameter carrying the same current. The magnetic field at distance $$(\mathrm{R})$$ from both the wires is 'B$$_1$$' and 'B$$_2$$' respectively. The relation between B$$_1$$ and B$$_2$$ is
In a CE transistor, a change of $$8.0 \mathrm{~mA}$$ in the emitter current produces a change of $$7.8 \mathrm{~mA}$$ in the collector current. What change in the base current is necessary to produce the same change in the collector current?