Electrical Resistance, Resistivity and Conductivity

IMPORTANT

Electrical Resistance, Resistivity and Conductivity: Overview

This topic covers concepts, such as, Resistivity of Various Materials, Types of Resistors, Resistance of a Cylindrical Shell between its Ends & Resistance of a Cylindrical Shell Across Inner and Outer Surface etc.

Important Questions on Electrical Resistance, Resistivity and Conductivity

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IMPORTANT

A physical quantity, associated with electrical conductivity, has the SI unit ohm-meter. Identify this physical quantity.

EASY
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The resistivity of a material is found to be 108Ω-m. Then the material would be

MEDIUM
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A cylindrical metallic wire is stretched to increase its length in such a way that the metallic wire changes its resistance by 6%. The percentage increase in its length is

EASY
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A metal wire of length L and radius r has a resistance R. If a wire of the same metal of length 2L and radius 3r is taken, then what will be its resistance?

MEDIUM
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A 1 m long wire is broken into two unequal parts X and Y. The X part of the wire is stretched into another wire W. Length of W is twice the length of X and the resistance of W is twice that of Y. Find the ratio of length of X andY.

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A wire of resistance R1 is drawn out so that its length is increased by twice of its original length. The ratio of new resistance to original resistance is:

EASY
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An aluminium wire is stretched to make its length, 0.4% larger. The percentage change in resistance is

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Two wires that are made up of two different materials whose specific resistances are in the ratio 2:3, length 3:4 and area 4:5. The ratio of their resistance is α. Write value of 8α.

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A wire-wound resistor is an electrical _____ component that limits current. 

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A wire wound resistor is an electrical passive device that limits or restricts _____ flow in a circuit.

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A wire wound resistor is an electrical passive component that limits current. 

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A wire of resistance 3 Ω is stretched to twice its original length. The resistance of the new wire will be:

HARD
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A thick wire is stretched, so that its length becomes two times. Assuming that there is no change in its density, then what is the ratio of change in resistance of wire to initial resistance of wire ?

EASY
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A solid metallic cuboid of homogeneous material having geometrical dimension as shown in the figure will have a ratio of resistances for the sense of current along xy and z directions respectively, equal to


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MEDIUM
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From the given figure what should be the magnitude of carbon resistor?

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A uniform wire of length l and radius R has a resistance of 100 Ω. It is recast into a wire of radius R2. The resistance of new wire will be-

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Two rods of copper and iron with the same cross sectional area are joined at S and a steady current I flows through the rods as shown in the figure.

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Choose the most appropriate representation of charges accumulated near the junction S.

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A wire of radius r has resistance R. If it is stretched to a wire of radius r2, then the resistance of the wire becomes: