# Homework Help: Calculate the Resistance of the RC circuit so that LED just stays on

1. Jun 25, 2014

### rhiannynd

In a simple series circuit there is a 12V supply battery, 12μ6 F capacitor, a Resistor, and a 2v drop LED with an imax of 30mA. frequency is 10Hz
Calculate the resistance of the resistor so that the LED just stays on.

2. Relevant equations
Resistance of Capacitor Xc = 1/2∏fC
P=VI
V=IR
Impedence = √R^2+Xc^2

3. The attempt at a solution

Xc = 1/2∏x10x12x10^6
=1326.3 Ω
P=vxI
P = 12 x 0.03A
=0.36w

i have no idea what else to do ! any help would be greatly appreciated please please please
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jun 27, 2014

### rude man

A battery with 10 Hz? That's a new one on me.

3. Jun 29, 2014

### BvU

So, is Rhian (PS: welcome to PF) out of trouble now ?

4. Jun 30, 2014

### rude man

He/she doesn't seem interested in pursuing this fascinating ac battery problem, all the 'please pleases' notwithstanding ...