Chapter – 13
Q.1: Electrons leave a dry cell and flow through a lamp back to the cell. Which terminal the positive or negative is the one from which electrons leave the cell? In which direction is the conventional current?
Ans: Electrons leave the negative terminal of the cell and move towards the positive terminal. However, as a convention, the conventional current is assumed to be the consisted of positive electric charges moving from a positive terminal to the negative terminal change flowing through the area per unit time (I = q/t).
Q.2: Both p.d. and e.m.f. are measured in volts. What is the difference between these concepts?
Ans: P.d. is the work done per unit charge across resistor in a closed circuit. But e.m.f. the total p.d. across the external and internal resistance, it refers to a source of current and is greater than the potential drop in an external circuit. (e.m.f. p.d. + internal resistance drop)
