Posted by **Stephanie** on Wednesday, March 10, 2010 at 6:30pm.

A 9-Volt battery is used to charge a 280 mF capacitor over a 81 Ohms resistance.

How long will it take for the capacitor to reach 75% of its maximum charge?

What formula is relevant?

- Physical Science -
**sam**, Wednesday, March 10, 2010 at 10:26pm
charging the capacitor formula;

Q=Q max (1-e ^-t/RC)

Q=qmax= 0.75

solve for t

- Physical Science -
**anony mouse**, Thursday, March 11, 2010 at 3:42pm
So the Voltage is irrelevant?

- Physical Science -
**Sandra**, Thursday, March 11, 2010 at 10:25pm
Why wouldn't you use this formula?

Q=Qmax*e^(-t/RC)

## Answer this Question

## Related Questions

- physics - 9-Volt battery is used to charge a 375 mF capacitor over a 147 Ù ...
- Physic II - Suppose a capacitor of C=2.0 uF with no excess charge on it is ...
- Science - 1. What is the direction of charge flow when charging a capacitor? ...
- physics - A 2.0 micro Farad capacitor in a circuit in series with a resistance ...
- SCience - An RC-circuit has a time constant of 6x10-3 seconds. The capacitor ...
- Physics - An RC-circuit has a time constant of 6x10-3 seconds. The capacitor ...
- physics - Having trouble with this one: A capacitor having a capacitance of 10uF...
- Physics - Could someone please tell me what equations i am suppose to use to ...
- Physics Help! - A 220 uF capacitor with a 10% tolerance rating is charged. The ...
- Physics - A capacitor of capacitance C= 10mF, is charged using a battery of ...