A single–loop circuit consists of a cell of emf and internal resistance supplying…

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

Problem

A single–loop circuit consists of a cell of emf

E

and internal resistance

r

supplying current to three series resistors

R_1

R_2

and a variable resistor

R_3

. (i) Derive an expression for the circuit current

I

in terms of

E

r

R_1

R_2

and

R_3

. (ii) For

E = 10\,\text{V}

r = 0.50\,\Omega

R_1 = 3.0\,\Omega

R_2 = 4.0\,\Omega

the current is required to be

0.50\,\text{A}

. Calculate the value of

R_3

that must be inserted. (iii) Using the value of

R_3

obtained in part (ii), determine the potential difference across

R_2