Two resistors of and are connected in series with an unknown resistor to a ideal dc source

PHYSICS · Subjective · A Level · Physics · Electricity · Electricity

Problem

Two resistors of

8\,\Omega

and

12\,\Omega

are connected in series with an unknown resistor

R_{x}

to a

30\,\text{V}

ideal dc source. The steady current in the circuit is found to be

1.0\,\text{A}

. (i) Calculate the equivalent resistance of the series combination. (ii) Determine the value of the unknown resistor

R_{x}

. (iii) Find the power dissipated in

R_{x}

. (iv) If

R_{x}

were to be replaced by a wire of negligible resistance, by what factor would the circuit current change?