Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
Readings for two conductors:
Find for each reading. Which one obeys Ohm's law?
Ohm's law: at a steady temperature, . So and , with in ohms (). The V-I graph of such a conductor is a straight line through the origin; its slope is .
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The resistor. , and every reading gives .
Step 2. The bulb. , , then : the ratio grows.
Answer: the resistor obeys Ohm's law, with . The bulb does not: its resistance rises as it heats up.
Check. The resistor's V-I graph is a straight line; the bulb's curves upward.
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