An electron with kinetic energy $K _{1}$ enters between parallel plates of a capacitor at an angle $'\alpha'$ with the plates. It leaves the plates at angle $' \beta '$ with kinetic energy $K _{2}$. Then the ratio of kinetic energies $K _{1}: K _{2}$ will be ....... .
$\frac{\sin ^{2} \beta}{\cos ^{2} \alpha}$
$\frac{\cos ^{2} \beta}{\cos ^{2} \alpha}$
$\frac{\cos \beta}{\cos \alpha}$
$\frac{\cos \beta}{\sin \alpha}$
A capacitor of capacity $C$ is connected with a battery of potential $V$ in parallel. The distance between its plates is reduced to half at once, assuming that the charge remains the same. Then to charge the capacitance upto the potential $V$ again, the energy given by the battery will be
A $5\, \mu F$ capacitor is charged fully by a $220\,V$ supply. It is then disconnected from the supply and is connected in series to another uncharged $2.5\;\mu F$ capacitor. If the energy change during the charge redistribution is $\frac{ X }{100} \;J$ then value of $X$ to the nearest integer is$.....$
A capacitor $4\,\mu F$ charged to $50\, V$ is connected to another capacitor of $2\,\mu F$ charged to $100 \,V$ with plates of like charges connected together. The total energy before and after connection in multiples of $({10^{ - 2}}\,J)$ is
Two insulated metallic spheres of $3\,\mu F$ and $5\,\mu F$ capacitances are charged to $300\, V$ and $500\, V$ respectively. The energy loss, when they are connected by a wire is
A variable condenser is permanently connected to a $100$ $V$ battery. If the capacity is changed from $2\,\mu \,F$ to $10\,\mu \,F$, then change in energy is equal to