<span>A coil is used to step up the electric potential difference using the principle of induction.</span>
Explanation:
Given that,
(a) Work done by the electric field is 12 J on a 0.0001 C of charge. The electric potential is defined as the work done per unit charged particles. It is given by :



(b) Similarly, same electric field does 24 J of work on a 0.0002-C charge. The electric potential difference is given by :



Therefore, this is the required solution.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.
Answer:
The voltage will be 0.0125V
Explanation:
See the picture attached