Resistors and Ohm's Law Video Lessons

Concept

# Problem: A copper wire is stretched so that its length increases and its diameter decreases. As a result, A. The wire's resistance decreases, but its resistivity stays the same. B. The wire's resistivity decreases, but its resistance stays the same. C. The wire's resistance increases, but its resistivity stays the same. D. The wire's resistivity increases, but its resistance stays the same.

###### FREE Expert Solution

Resistance is defined as the opposition of the flow of electric current in a circuit.

The resistance of a wire is expressed as:

$\overline{){\mathbf{R}}{\mathbf{=}}\frac{\mathbf{\rho }\mathbf{l}}{\mathbf{A}}}$, where R is the resistance, ρ is the resistivity, l is the length of the wire, and A is the cross-sectional area of the wire.

When the length of the wire is increased and the diameter is decreased, we can get the resistance as follows:

A = πr2, where r is the radius of the wire, given by r = d/2

A = π(d/2)2

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###### Problem Details

A copper wire is stretched so that its length increases and its diameter decreases. As a result,

A. The wire's resistance decreases, but its resistivity stays the same.

B. The wire's resistivity decreases, but its resistance stays the same.

C. The wire's resistance increases, but its resistivity stays the same.

D. The wire's resistivity increases, but its resistance stays the same.