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A battery of emf 2 V and negligible internal resistance is connected across a uniform wire of length 10 m and resistance 30 Ω . The appropriate terminals of a cell of emf 1.5 V and internal resistance 1 Ω is connected to one end of the wire and the other terminal of the cell is connected through a sensitive galvanometer to a slider on the wire. What is the length of the wire that will be required to produce zero deflection of the galvanometer? How will the balancing length change?

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(a) When a coil of resistance 5 Ω is placed in series with the accumulator.

(b) The cell of 1.5 V is shunted with 5 Ω resistor?

Important Questions on Electrical Measuring Instruments

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JEE Advanced
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In the circuit shown in the figure, resistors X and Y, each with resistance R, are connected to a 6 V battery of negligible internal resistance. A voltmeter, also of resistance R, is connected across Y.

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What is the reading of the voltmeter?

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In the shown arrangement of a meter bridge, if AC corresponding to null deflection of galvanometer is x, what would be its value if the radius of the wire AB is doubled?
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The length of a wire of a potentiometer is 100 cm and the emf of its standard cell is E volt. It is employed to measure the emf of a battery whose internal resistance is 0.5 Ω. If the balance point is obtained at l=30 cm from the positive end, the emf of the battery is, 
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JEE Advanced
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In a meter bridge experiment, the null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X<Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y?
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In the circuit shown in figure, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be

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The resistance of a galvanometer is 10 Ω. It gives full-scale deflection when 1 mA current is passed. The resistance connected in series for converting it into a voltmeter of 2.5 V will be
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An ideal ammeter (zero resistance) and an ideal voltmeter (infinite resistance) are connected as shown in the figure. The ammeter and the voltmeter readings are
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A constant 60 V dc supply is connected across two resistors of resistance 400 kΩ and 200 kΩ. What is the reading of the voltmeter, also of resistance 200 kΩ, when connected across the second resistor as shown in figure?
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