JEE PYQ: Current Electricity Question 40
Question 40 - 2019 (08 Apr 2019 Shift 2)
A cell of internal resistance $r$ drives current through an external resistance $R$. The power delivered by the cell to the external resistance will be maximum when:
(1) $R = 0.001,r$
(2) $R = 1000,r$
(3) $R = 2r$
(4) $R = r$
Show Answer
Answer: (4)
Solution
$i = \frac{\varepsilon}{R+r}$, $P = i^2 R = \left(\frac{\varepsilon}{R+r}\right)^2 R$. For maximum, $\frac{dP}{dR} = 0$ gives $R = r$.
BETA
