Question

A cell drives a current through a circuit. The emf of the cell is equal to the work done in moving unit charge

• A. from the positive to the negative plate of the cell
• B. from the positive plate, back to the positive plate
• C. from the negative plate, back to the negative plate
• D. from any point in the circuit back to the same point

Answer 1

Answer: (B), (C)

The correct options are
B from the positive plate, back to the positive plate
C from the negative plate, back to the negative plate

When a cell is connected in the circuit emf is the force required to circulate the current from positive terminal to negative one i.e. to circulate the electron(-ve charge) from negative terminal to positive one. Also, in case of minority charges to circulate the hole(+ve charge) from positive terminal to negative one. Hence, the emf of the cell is equal to the work done in moving unit charge from the positive plate, back to the positive plate or from the negative plate, back to the negative plate.