$A$ magnetic needle is kept in a non-uniform magnetic field. It experiences

$A$ cell of $emf$ $E$ and internal resistance $r$ is connected in series with an external resistance $nr$. Then,the ratio of the terminal potential difference to $emf$ is

In a compound microscope,the focal length of the objective lens is $f_o = 1.2 \ cm$ and the focal length of the eyepiece is $f_e = 3.0 \ cm$. When the object is kept at $u_o = -1.25 \ cm$ in front of the objective,the final image is formed at infinity. The magnifying power of the compound microscope is:

Which of the following metals belong to the same group in the periodic table?

Two wires are made of the same material and have the same volume. However,wire $1$ has cross-sectional area $A$ and wire $2$ has cross-sectional area $3A$. If the length of wire $1$ increases by $\Delta x$ on applying force $F$,how much force is needed to stretch wire $2$ by the same amount?

The stress versus strain graphs for wires of two materials $A$ and $B$ are as shown in the figure. If ${Y_A}$ and ${Y_B}$ are the Young's moduli of the materials,then