A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is

The correct answer is $\boxed{\text{C. 200 joules}}$.

The energy stored in a capacitor is given by the equation:

$$E = \frac{1}{2}CV^2$$

where $C$ is the capacitance in farads, $V$ is the potential difference in volts, and $E$ is the energy stored in joules.

In this case, we are given that $C = 5 \mu F$ and $V = 10,000 V$. Substituting these values into the equation, we get:

$$E = \frac{1}{2}(5 \mu F)(10,000 V)^2 = 200 \text{ joules}$$

Therefore, the energy stored in the capacitor is 200 joules.

Option A is incorrect because it is half the correct value. Option B is incorrect because it is twice the correct value. Option D is incorrect because it is four times the correct value.