Question

Five cells each of EMF 5 V are connected in series. The combination in series is joined to an ammeter of negligible resistance, a 1.6 Ω resistor, a 0.8 Ω resistor and an unknown resistor R 1 as shown in figure. The current in the circuit is 10 A. Assume the voltmeter to be ideal. 5. Find the value of R

Answer 1

(i) The resistance in the circuit

= (1.6 + 4 x 0.1 + R1)Ω = (2 + R1)Ω

(ii) Total e.m.f. = No. of cell x e.m.f of each cell = 4 x 2 = 8V.

(iii) Current in main circuit i = Total e.m.f/Total resistance

Or 2 = 8/2 + R1

∴ R1 = 4/2 = 2Ω.

(iv) The p.d. across, R1 = V = iR1 = 2 x 2 = 4V.

Answer 2

$answer \: is \: 0.1 Ω$

$full \: explanation \: is \: given \: in \: the \: attachment$