Q1. The figure shows a plot of current versus voltage for two different materials, A and B. At a particular voltage , which material has the greater resistance? Explain your reasoning.

Background

Topic: Ohm's Law and Resistance

This question tests your understanding of how to interpret current-voltage (I-V) graphs for different materials, and how resistance is related to the slope of these graphs. It also explores the concept of Ohmic and non-Ohmic materials.

Key Terms and Formulas

• Ohm's Law:

• Resistance ():

• Ohmic Material: A material that has a linear I-V relationship (constant resistance).

• Non-Ohmic Material: A material with a nonlinear I-V relationship (resistance changes with voltage/current).

Step-by-Step Guidance

1. At voltage , draw a horizontal line to the curves for both materials A and B. Note the current values for each material at this voltage.

2. Recall that resistance at a given point is . For the same voltage , compare the currents and for materials A and B.

3. If a material has a lower current at the same voltage, its resistance is higher (since increases as decreases for fixed ).

4. Examine the slopes of the I-V curves at . For a linear (Ohmic) material, the slope is constant; for a nonlinear (non-Ohmic) material, the slope changes.

5. Set up the ratio and , and determine which is greater based on the current values at .

Try solving on your own before revealing the answer!