# Homework Help: Capacitance and voltage relationship

1. Jun 5, 2012

### jsmith613

1. The problem statement, all variables and given/known data

The actual value of the capacitor Rahal will receive may be different from the value the
catalogue states. The manufacturer guarantees that the maximum percentage difference
below/above the catalogue value will be –10% / +50%. Rahal orders one of the 400 V 1000 µF capacitors. Within what range will its actual value lie?

2. Relevant equations

Q=CV
therefore C is inversely proportional to V
3. The attempt at a solution

I would say:
1100µF = max
500µF = min

900µF = min
1500µF = max

WHY???

thanks

Last edited: Jun 5, 2012
2. Jun 5, 2012

### Martinet

The stated capacitance is 1000.

The possible variance is -10% to +50%.

What is 10% of 1000 subtracted from 1000?
What is 50% of 1000 added to one thousand?

3. Jun 5, 2012

### jsmith613

but the variance is for the voltage...

4. Jun 5, 2012

### Martinet

Where is that stated?

Additionally, bearing in mind that I'm yet to study capacitors in any level of detail, does the voltage not correspond to a maximum input voltage that the device can handle without being damaged, destroyed, or at least cease to function?

5. Jun 5, 2012

### jsmith613

The manufacturer guarantees that the maximum percentage difference
below/above the catalogue value will be –10% / +50%.

6. Jun 5, 2012

### Martinet

Are you reading "percentage difference" as "percentage potential difference" or something similar?

7. Jun 5, 2012

yes...oops
thanks