Which one of the following is the pair of equivalent circuits?

A ferromagnetic material is heated above its curie temperature. The correct statement from the following is that

The number of photoelectrons emitted for light of frequency $v$ (higher than the threshold frequency $\left(v_0\right)$ is proportional to

The amount of work done in increasing the voltage across the plates of a capacitor form 5 V to 10 V is ' W '. The work done in increasing it from 10 V to 15 V will be (nearly)