EASY
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Rheostat is made by

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Important Questions on Current Electricity

EASY
The resistance of a wire is 4 Ω. If the length of the wire is made double and the area of cross-section is made half, then the new resistance will be :
MEDIUM

The potential difference between the two ends of a conductor is V, and the current flowing through the conductor is I. At a constant temperature, which of the following statement is true for the conductor?

HARD

In the given circuit the voltmeter reads 5V. The resistance of the voltmeter in Ohm is.

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EASY

Following figures shows graph of I-V. Which graph is correct according to Ohm's law?

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HARD

The resistance of rheostat shown in the figure is 0-30 Ω, Neglecting the resistance of ammeter and connecting wire the minimum and maximum currents through the ammeter will be

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EASY
An unknown circuit draws a current of 2 A from a 12 V battery. Its equivalent resistance is
EASY

Consider an infinite grid with square cells. The resistance between two adjacent joints is  R. Find the net resistance Rnet of the whole grid between two points A & B.

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EASY

For a cell, a graph is plotted between the potential difference V across the terminals of the cell and current I drawn from the cell (see fig.) The emf and internal resistance of the cell are E and r respectively, then :

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HARD
Consider the following Assertion and the Reason and select the correct alternative: Assertion (A): Alloys are used in electric heating devices. Reason (R): Alloys do not oxidise readily at high temperature.
EASY
Determine the potential difference between ends of a wire of resistance 5 Ω, if 720 C charge passes through it per minute.
EASY
If a wire of 1 m length and 10 Ω resistance is stretched to 3 m length by keeping its volume intact. Now the resistance of the wire will be :
EASY

V-I graph for parallel and series combinations for two identical resistors are as shown in figure.Which graph represents parallel combination?

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EASY
In one circuit, resistance of wire is 10 Ω. If it is connected with 2.5 V battery, how much electric current will flow through it?
EASY
Name a substance whose resistance decreases with the increase in temperature.