A sphere of radius $1\,cm$ has potential of $8000\,V$, then energy density near its surface will be
$64 \times {10^5}\,J/{m^3}$
$8 \times {10^3}\,J/{m^3}$
$32\,J/{m^3}$
$2.83\,J/{m^3}$
In which of the following stores maximum energy ?
A parallel plate capacitor having a plate separation of $2\, mm$ is charged by connecting it to a $300\, V$ supply. The energy density is.....$J/m^3$
Charge $'q'$ on a capacitor varies with voltage $'V'$ as shown. The area of $\Delta OPM$ represents
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
A piece of cloud having area $25 \times {10^6}\,{m^2}$ and electric potential of ${10^5}$ $volts$. If the height of cloud is $0.75\,km$, then energy of electric field between earth and cloud will be.....$J$