Three equal charges are placed at the corners of an equilateral triangle. Which of the graphs below correctly depicts the equally-spaced equipotential surfaces in the plane of the triangle? (All graphs have the same scale.)

Energy of electrons can be increased by allowing them

The work done to take an electron from rest where potential is $-60\, V$ to another point where potential is $-20\, V$ is given by.....$eV$.

$A$ particle $A$ has a charge of $+q$ and a particle $B$ has a charge of $+9q$. Both particles have the same mass $m$. If both particles are released from rest through the same potential difference,the ratio of their speeds will be .......

Two point charges $q_1 = 4 \times 10^{-8} \ C$ and $q_2 = -6 \times 10^{-8} \ C$ are placed at points $A$ and $B$ respectively,which are $50 \ cm$ apart. At what distance from point $A$ on the line $AB$ is the electric potential zero (in $cm$)?

Define electron volt and convert it into Joule unit.