Question

Two resistors of 2 Ω and 4 Ω are first connected first in series and
then in parallel. The ratio of the equivalent resistance for series to
parallel is
I)9 / 2 ii) 2 / 9 iii) 8 / 1 iv ) none of them

Answer 1

Answer:

Correct answer is option (i) 9/2

Explanation:

First case : When connected in series

$R_s = 2 + 4 = 6 \: \: \: ohm$

Second case: When connected in parallel

$R_p = {( \frac{1}{2} + \frac{1}{4} })^{ - 1} = {( \frac{3}{4} })^{ - 1} = \frac{4}{3} \: \: ohm$

Now the ratio is :

$\frac{R_s}{R_p} = \frac{6}{ \frac{4}{3} } = 6 \times \frac{3}{4} = \frac{9}{2}$