An electric charge $q$ is placed at the centre of a cube of side $\alpha $. The electric flux on one of its faces will be

A charge $Q$ is fixed at a distance $d$ in front of an infinite metal plate. The lines of force are represented by

The circular wire in figure below encircles solenoid in which the magnetic flux is increasing at a constant rate out of the plane of the page. The clockwise emf around the circular loop is $\varepsilon_{0}$. By definition a voltammeter measures the voltage difference between the two points given by $V_{b}-V_{a}=-\int \limits_{a}^{b} E \cdot d s$ We assume that $a$ and $b$ are infinitesimally close to each other. The values of $V_{b}-V_{a}$ along the path $1$ and $V_{a}-V_{b}$ along the path $2$ , respectively are

The electric field in a certain region is acting radially outward and is given by $E =Ar.$ A charge contained in a sphere of radius $'a'$ centred at the origin of the field, will be given by

A charge $Q$ is enclosed by a Gaussian spherical surface of radius $R$. If the radius is doubled, then the outward electric flux will

An electrostatic field line leaves at an angle $\alpha$ from point charge $q_{1}$ and connects with point charge $-q_{2}$ at an angle $\beta\left(q_{1}\right.$ and $q_{2}$ are positive) see figure below. If $q_{2}=\frac{3}{2} q_{1}$ and $\alpha=30^{\circ}$, then