A circuit consists of three resistors with values ,

PHYSICS · Multi-part · A Level · Physics · Electricity · Electricity

Problem

A circuit consists of three resistors with values

10\,\Omega

15\,\Omega

, and

30\,\Omega

. The

10\,\Omega

and

30\,\Omega

resistors are connected in parallel between points

C

and

D

. This parallel combination is then connected in series with the

15\,\Omega

resistor between terminals

A

and

B

. While the circuit is operating, the experimenter accidentally connects an additional ideal conducting wire directly between points

C

and

D

. The wire has zero resistance and remains in place. (1) Explain qualitatively how the presence of the additional wire affects the current distribution in the branches that originally contained the

10\,\Omega

and

30\,\Omega

resistors. (2) Calculate the equivalent resistance between terminals

A

and

B

(i) before and (ii) after the wire is added. Show all relevant steps. (3) Immediately after the wire is added, determine the electrical power dissipated in the

30\,\Omega

resistor. Justify your answer.

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