# Homework Help: Instantaneous current in a reisistor, capacitor and inductor

1. Nov 27, 2012

### lisanoir

1. The problem statement, all variables and given/known data
a resistor, a capacitor and an inductor are connected in parallel to a source of oscillating EMF of frequency 955hz and amplitude of 1.0x10^3 V. the resistance of the resistor is 200Ω. what is the maximal instantaneous current in the resistor? if we want to make a maximum instantaneous currents in the capacitor and in the inductor equal to that in the resistor, what values of the capacitance and the inductance must we select?

2. Relevant equations
Irms= ΔVrms/(R^2+(xl-xc)^2)^(1/2)
Irms= Imax/(2)^(1/2)= 0.707Imax
xl=wl
xc=1/wc
frequency= 955hz (2∏f)

3. The attempt at a solution
amplitude is given, therefore, we can consider this Vmax

Irms= 1.0x10^3V/ (200^2+(xl-xc)^2)^(1/2)

2. Nov 27, 2012

### Staff: Mentor

For instantaneous values you won't need to deal with rms values. You'll want the instantaneous peaks of the voltages and/or currents.

If the input voltage is 1000V*cos(ωt), what's the maximum voltage that can appear across the resistor?