Two resistors of $2\,\Omega$ and $3\,\Omega$ are in series. What is the equivalent resistance?

Series resistances add directly: $2 + 3 = 5\,\Omega$.

Correct answer: $5\,\Omega$

If $I = 2\,\text{A}$ and $R = 4\,\Omega$, what is the voltage?

Using $V = IR$, we get $V = 2 \times 4 = 8\,\text{V}$.

Correct answer: 8 V

A $12\,\text{V}$ supply is across a $6\,\Omega$ resistor. What power is dissipated?

Use $P = \frac{V^2}{R} = \frac{12^2}{6} = 24\,\text{W}$? Wait carefully: $144/6 = 24\,\text{W}$. So the correct answer is option 2.

Correct answer: $12\,\text{W}$

What is the total resistance of two equal resistors of $10\,\Omega$ in parallel?

For equal resistors in parallel, the equivalent resistance is half of one resistor: $10/2 = 5\,\Omega$.

Correct answer: 5 Ω