Question

Refer to Ohm's Law given in the previous question.

If the voltage in a circuit is 35+j12 volts and the resistance is 2+j4 ohms, what is the current?

A) −596+j293 amps
B) −196+j293 amps
C) 33−j8 amps
D) 5910−j295 amps
E) 37+j16 amps
F) 118−j164 amps

Answer 1

Ohm's Law:  voltage = resistance times current.  Here we know voltage and resistance, but must calculate the current.

current = voltage / resistance

                            35 + 12j

Here, current = --------------- amps

                           2(1+2j)

We must rationalize the denominator (remove 'j' from the denom.).  To do this, multiply numerator and denominator of the above fraction by (1-2j), obtaining:

(25+12j)(1-2j)       25-50j+12j+24        49 - 36j

------------------- = ------------------------ = ---------------- ohms (answer)

2(1 + 4)                         10                       10