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Current Electricity

Question
CBSEENPH12039908
Wired Faculty App

The resistance of the four arms P, Q, R and S a Wheatstone's bridge are 10Ω, 30Ω and 90Ω respectively. The emf and internal resistance of the cell are 7V and 5Ω respectively. If the galvanometer resistance is 50Ω, the current drawn from the cell will be

  • 1.0 A

  • 0.2 A

  • 0.1 A

  • 2.0 A

Solution

B.

0.2 A

Effective resistance,
straight R subscript eff space equals space fraction numerator 40 space straight x space 120 over denominator 120 plus 40 end fraction space equals space 4800 over 160 space equals space 30 straight capital omega therefore comma Current space straight I space equals space fraction numerator 7 over denominator left parenthesis 30 plus 5 right parenthesis end fraction space equals space 7 over 35 space equals space 0.2 straight A open square brackets therefore space straight I space equals space fraction numerator straight E over denominator straight R plus straight r end fraction close square brackets

Some More Questions From Current Electricity Chapter

What conclusion can you draw from the following observations on a resistor made of alloy manganin?

Current A

Voltage V

Current A

Voltage V

0.2

0.4

0.6

0.8

1.0

2.0

3.94

7.87

11.8

15.7

19.7

39.4

3.0

4.0

5.0

6.0

7.0

8.0

59.2

78.8

98.6

118.5

138.2

158.0

Answer the following questions:
A steady current flows in a metallic conductor of non-uniform cross-section. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed?

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