Physics 2000 JAMB Past Questions - Question 35: A radio is operated by eight cells each of e.m.f. 2.0V connected in series. If two of the cells are wrongly connected, the net e.m.f. of the radio is

Correct Answer

B

Explanation

Net e.m.f =(8*2)-(2*2)=12VWhen eight cells with an electromotive force (e.m.f.) of 2.0V each are connected in series, their total e.m.f. adds up. So, the net e.m.f. of the radio is:When cells are connected in series, the total electromotive force (EMF) is the sum of the individual EMFs. In this case, there are eight cells, each with an EMF of 2.0V, connected in series.

So, the initial net EMF of the radio is:

Net EMF = 2.0V + 2.0V + 2.0V + 2.0V + 2.0V + 2.0V + 2.0V + 2.0V
        = 16.0V

However, if two of the cells are wrongly connected, it means that their polarities are reversed. This reversal of polarity effectively subtracts their individual EMFs from the net EMF.

So, the net EMF of the radio with two cells wrongly connected would be:

Net EMF = 16.0V - 2.0V - 2.0V
        = 12.0V

Therefore, the net EMF of the radio, when two cells are wrongly connected, would be 12.0V.

Net e.m.f. = 8 * 2.0V = 16.0V

However, if two of the cells are wrongly connected, it means that their polarities are reversed. When two cells with reversed polarities are connected in series, they effectively subtract their voltages from the total. In this case, the e.m.f. of the two cells with reversed polarities will be subtracted from the total e.m.f.

So, the net e.m.f. with two cells wrongly connected is:

Net e.m.f. = 16.0V - 2.0V - 2.0V = 12.0V

Therefore, the net e.m.f. of the radio with two cells wrongly connected is 12.0V.