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:

  • Option 1)

    2.0 A

  • Option 2)

    1.0 A

  • Option 3)

    0.2 A

  • Option 4)

    0.1 A

 

Answers (2)

As discussed in @8173

Req = \frac{40\times 120}{40+120}\:\Omega

I = \frac{V}{R} =\frac{7}{5+\frac{40\times 120}{40+120}}

I = \frac{7}{5+30} \Rightarrow I = \frac{1}{5} = 0.2A


Option 1)

2.0 A

This answer is incorrect

Option 2)

1.0 A

This answer is incorrect

Option 3)

0.2 A

This answer is correct

Option 4)

0.1 A

This answer is incorrect

The resistance in the two arms of the metre Bridge are 5 ohm and 6 ohm respectively when the resistance R is shunted with unequal resistance the new balance point is at 1.6 L1 the resistance R is

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