If the electric flux entering and leaving an enclosed surface respectively is ${\phi _1}$ and ${\phi _2}$ the electric charge inside the surface will be
$\left( {{\phi _2} - {\phi _1}} \right){\varepsilon _0}$
$\frac{{\left( {{\phi _1} + {\phi _2}} \right)}}{{{\varepsilon _0}}}$
$\frac{{\left( {{\phi _2} - {\phi _1}} \right)}}{{{\varepsilon _0}}}$
$\left( {{\phi _1} + {\phi _2}} \right){\varepsilon _0}$
In the circuit shown, a potential difference of $60\,V$ is applied across $AB$. The potential difference between the point $M$ and $N$ is.....$V$
Four charges are placed at the circumference of a dial clock as shown in figure. If the clock has only hour hand, then the resultant force on a charge $q_0$ placed at the centre, points in the direction which shows the time as
Two equal negative charges $-q$ are fixed at points $(0, -a)$ and $(0, a)$ in the $x-y$ plane. A positive charge $Q$ is released from rest at a point $(2a, 0)$. The charge $Q$ will
Three identical uncharged metal spheres are at the vertices of an equilateral triangle. One at a time, a small sphere is connected by a conducting wire with a large metal sphere that is charged. The center of the large sphere is in the straight line perpendicular to the plane of equilateral triangle and passing through its centre (see figure). As a result, the first small sphere acquires charge $q_1$ and second charge $q_2 (q_2 < q_1)$ . The charge that the third sphere $q_3$ will acquire is (Assume $l >> R$ , $l >> r$ , $d >> R$ , $d >> r$ )
Two spheres of radius $a$ and $b$ respectively are charged and joined by a wire. The ratio of electric field of the spheres is