Figure shows variation of Coulomb force $(F)$ acting between two point charges with $\frac{1}{r^2}, r$ being the separation between the two charges $\left(q_1, q_2\right)$ and $\left(q_2\right. q_3$ ). If $q_2$ is positive and least in magnitude, then the magnitudes of $q_1, q_2$ and $q_3$ are such that

Two wires $P$ and $Q$ are made of the same material. The wire $\mathbf{Q}$ has twice the diameter and half the length as that of wire $P$. If the resistance of wire $P$ is $R$, the resistance of the wire $Q$ will be

A 1 cm segment of a wire lying along $x$-axis carries current of 0.5 A along $+x$ direction. A magnetic field $\vec{B}=(0.4 \mathrm{mT}) \hat{j}+(0.6 \mathrm{mT}) \hat{k}$ is switched on, in the region. The force acting on the segment is

A coil has 100 turns, each of area $0.05 \mathrm{~m}^2$ and total resistance $1.5 \Omega$. It is inserted at an instant in a magnetic field of 90 mT , with its axis parallel to the field. The charge induced in the coil at that instant is