A 25 Ω resistor carries a current of 0.28 A…

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Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

A $25\ \Omega$ resistor carries a current of $0.28\ \text{A}$ . What is the potential difference across it? What current flows if it is joined to $10.5\ \text{V}$ ?

Need a reminder? The key ideaShow

Ohm's law: at a steady temperature, $V = IR$ . So $I = \dfrac{V}{R}$ and $R = \dfrac{V}{I}$ , with $R$ in ohms ( $1\ \Omega = 1\ \text{V/A}$ ). The V-I graph of such a conductor is a straight line through the origin; its slope is $R$ .

The worked solution

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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.

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