Question

A parallel plate capacitor is charged to voltage V and then disconnected from the battery. Leopold says that the voltage will decrease if the plates are pulled apart. Gerhardt says that the voltage will remain the same. Which one, if either, is correct, and why? 1. Gerhardt, because the maximum voltage is determined by the battery.

2. Gerhardt, because the charge per unit area on the plates does not change.

3. Leopold, because charge is transferred from one plate to the other when the plates are separated.

4. Leopold, because the force each plate exerts on the other decreases when the plates are pulled apart.

5. Neither, because the voltage increases when the plates are pulled apart.

Answer 1

answers, the correct one is 5

Step-by-step explanation:

For this exercise let's use the definition of capacitance

C =
`(Q)/(\Delta V)`

also the capacitance for a parallel plate capacitor is

C =
`(\epsilon_o A)/(d)`

therefore we can match these two expressions

\frac{\epsilon_o A}{d} = \frac{Q}{\Delta V}

`\Delta V = (Q)/(\epsilon_o A) d`

We can see that the area and charge of the condensate do not change when the plates are separated, therefore the potential difference increases with distance.

When reviewing the different answers, the correct one is 5 : Neither, because the voltage increases when the plates are pulled apart.