Introduction to Electric Circuits

3.12 Problems 63

Figure 3.42

,,AIf

1s 6s

4 I |! J

A

T

B

12.[-] 18V

4 In the circuit of Fig. 3.43 the resistor R is variable from 0 to 40 11.

Determine the limits of the current through it.

Q ~

12V

5 The resistor R in the circuit of Fig. 3.44 is variable from 2 1~ to 200 fl.

Determine (a) the maximum current through it, (b) the minimum current

through it and (c) the value of its resistance when the current through it is

100 mA.

Figure 3.44

Figure 3.43

4V

_I

L

20~

I I

5~ 5~

I

6 Use Norton's theorem to calculate the current in each of the branches of

the circuit of Fig. 3.45 shown overleaf.