Practice Resistance in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A measure of how much a material opposes the flow of electric current. Measured in ohms (\(\Omega\)).

Resistance is like friction for electricity — a narrow pipe resists water flow more than a wide one.

Example 1

easy
A resistor carries 2 \text{ A} of current when 10 \text{ V} is applied across it. What is the resistance?

Example 2

medium
A wire has length 2 \text{ m}, cross-sectional area 1 \times 10^{-6} \text{ m}^2, and resistivity \rho = 1.7 \times 10^{-8} \text{ } \Omega \cdot \text{m} (copper). What is its resistance?

Example 3

easy
If the resistance of a wire doubles and the voltage stays the same, what happens to the current?

Example 4

medium
A wire has resistance R = \rho \frac{L}{A}. If you replace a wire with one that is twice as long and has three times the cross-sectional area (same material), how does the resistance change?
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