Which of the following relations correctly gives the equivalent resistance of three…

PHYSICS · Single correct · A Level · Physics · Electricity · Electricity

Problem

Which of the following relations correctly gives the equivalent resistance

R_{\text{eq}}

of three resistors

R_1,\;R_2

and

R_3

connected in parallel? (a)

\displaystyle R_{\text{eq}}=\frac{R_1R_2+R_2R_3+R_3R_1}{R_1+R_2+R_3}

(b)

R_{\text{eq}}=R_1+R_2+R_3

(c)

\displaystyle \frac{1}{R_{\text{eq}}}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}

(d)

\displaystyle R_{\text{eq}}=\sqrt[3]{R_1R_2R_3}