$ \Rightarrow {k_S} = \frac{{{k_1}{k_2}}}{{{k_1} + {k_2}}}$.

$(A)$ Restoring torque in case $A =$ Restoring torque in case $B$
$(B)$ Restoring torque in case $A < $ Restoring torque in case $B$
$(C)$ Angular frequency for case $A > $ Angular frequency for case $B$.
$(D)$ Angular frequency for case $A < $ Angular frequency for case $B$.


$y = A\,\cos \,\omega t\,\cos \,2\omega t + A\,\sin \,\omega t\,\sin \,2\omega t$.
Than the nature of the function is
If a student plots graphs of the square of maximum charge $( Q_{Max} ^2 )$ on the capacitor with time$(t)$ for two different values $L_1$ and $L_2 (L_1 > L_2)$ of $L$ then which of the following represents this graph correctly? (plots are schematic and not drawn to scale)
