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The resistance 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
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- 0.2 A
- 0.1 A
- 2. 0 A
- 1. 0 A
Correct Option: A
Given : V = 7 V
r = 5Ω
| Req = | 40 x 120 | Ω |
| 41 + 120 |
| = | 7 | = | 1 | = 0.2A. |
| 5 + 30 | 5 |
