10. D.C Circuits

Question 1

circuit symbols

Question 2

electromotive force (e.m.f.)

Answer 2

electromotive force (e.m.f.) of a source as energy transferred per unit charge in driving charge around a complete circuit.

Question 3

distinguish between e.m.f. and potential difference (p.d.)

Question 4

understand the effects of the internal resistance of a source of e.m.f. on the terminal potential difference

Question 5

Kirchhoff’s first law

Answer 5

it is a consequence of conservation of charge.
-sum of currents entering a junction=sum of currents leaving the same junction.
- algebraic sum of currents at a junction is zero.

Question 6

Kirchhoff’s second law

Answer 6

it is a consequence of conservation of charge.
-sum of electromotive forces=sum of potential differences around a closed loop.
-the algebraic sum of the p.d.s and e.m.f.s is zero around a closed loop.e

Question 7

derive, using Kirchhoff’s laws, a formula for the combined resistance of two or more resistors in series

Question 8

derive, using Kirchhoff’s laws, a formula for the combined resistance of two or more resistors in parallel

Question 9

principle of a potential divider circuit

Question 10

principle of the potentiometer

Answer 10

a means of comparing potential differences

Question 11

use of a galvanometer in null methods

Question 12

use of thermistors and light dependent resistors in potential dividers to provide a potential
difference that is dependent on temperature and light intensity