# Homework Help: RLC in an AC circuit

1. Aug 20, 2010

### pat666

1. The problem statement, all variables and given/known data
For which of the following AC circuits does impedance depend on frequency? A circuit with
Check all that apply.
a resistor and inductor.
a resistor and capacitor.
only a resistor.

2. Relevant equations

3. The attempt at a solution
I think that for a capacitor and inductor the frequency would change the impedance but im not sure?????????
thanks for any help.

2. Aug 20, 2010

### rl.bhat

Impedance of the resistance only does not depend on the frequency.

3. Aug 20, 2010

### pat666

so I was right----- thanks--slightly off topic but I have another question
"A circular wire loop of wire has radius 2.3cm and resistance 0.045ohms . A magnetic field is perpendicular to the loop.
At what rate must the field change in order to induce a current of 1.4mA in the loop"
ie. magnetic field/change in time?

I have been searching my text book and cant find a formula thats relevant.
Would really appreciate some help.

4. Aug 20, 2010

### rl.bhat

Magnetic flux φ = EA, where E is electric field and A is the area of ring.

dφ/dt = A*dE/dt = V = IR.

5. Aug 20, 2010

### pat666

Thanls a lot rl.bhat