The resistances of the four arms P,Q, R and S in a Wheatstone's bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be :

Question

The resistances of the four arms P,Q, R and S in a Wheatstone's bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be : (A) 2.0 A (B) 1.0 A (C) 0.2 A (D) 0.1 A

Tardigrade Admin · Accepted Answer

Total resistance of Wheatstone bridge = ((40)(120)/40 + 120) = 30 Ω Current through cell = (7 V/( 5 +30) Ω ) = (1/5) A = 0.2 A

Q. The resistances of the four arms $P, Q, R$ and $S$ in a Wheatstone's bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be :

2.0 A

1.0 A

0.2 A

0.1 A

Total resistance of Wheatstone bridge
$= \frac{( 40 ) ( 120 )}{40 + 120} = 30Ω$
Current through cell = $\frac{7 V}{( 5 + 30 ) Ω} = \frac{1}{5} A = 0.2 A$

Q. The resistances of the four arms P,Q,R and S in a Wheatstone's bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be :