Exercise

The electrostatic force on a small sphere of charge $0.4 \mathrm{\mu }\mathrm{C}$ due to another small sphere of charge $–0.8 \mathrm{\mu }\mathrm{C}$ in the air is $0.2 \mathrm{N}.$ What is the force on the second sphere due to the first?

The network shown in figure is part of a complete circuit. If at a certain instant the current ($I$) is $5 \mathrm{A}$, and is decreasing at a rate of ${10}^3 \mathrm{A}/\mathrm{s}$, then $V_B-V_A$ is

A hot filament liberates an electron with zero initial velocity. The anode potential is $1200 \mathrm{V}$. The speed of the electron when it strikes the anode is

For uranium nucleus how does its mass vary with volume?

Which state of the triply ionised beryllium $\left(B{e}^{3+}\right)$ has the same orbital radius at that of the ground state of hydrogen?

An energy of $24.6 \mathrm{eV}$ is required to remove one of the electrons from a neutral helium atom. The energy (in $\mathrm{eV}$) required to remove both the electrons from a neutral helium atom is

Why is conduction easier in gases if the pressure is low? Will the conduction continue to improve if the pressure is made as low as nearly zero?

An immersion heater rated $1000 \mathrm{W}, 220 \mathrm{V}$ is used to heat $0.01 {\mathrm{m}}^3$ of water. Assuming that the power is supplied at $220 \mathrm{V}$ and $60\%$ of the power supplied is used to heat the water, how long will it take to increase the temperature of the water from $15°\mathrm{C}$ to $40°\mathrm{C}?$