1. Mar 25, 2007

### natural

1. The problem statement, all variables and given/known data[/b]
If the p.d across a capacitor is doubled, by what factor does the ehnergy stored change?

2. Mar 25, 2007

### hage567

What have you done so far? Show your work. What equation might be useful for question #1?

3. Mar 25, 2007

### natural

V = Q/C ? i dont really undersatnd the question

4. Mar 25, 2007

### hage567

That's not an equation for energy. You want $$U=(1/2)CV^2$$ where U is the stored energy, C is the capacitance, and V is the potential difference.

It's asking if the potential difference is doubled, how much does the energy stored in the capacitor change. So using that equation, if you double V, what happens to U?

5. Mar 25, 2007

### natural

ooh ok U doubles

6. Mar 25, 2007

### hage567

NO, look more closely. It's V squared, right?

7. Mar 25, 2007

### natural

increase by 4?

8. Mar 25, 2007

### hage567

That's better.