Question

What is (a) the highest, (b) the lowest total resistance that can be secured
by combinations of four coils of resistance 4 ohm, 8 ohm, 12 ohm, 24 ohm?​

Answer 1

Answer:

highest resistance =48ohm

lowest resistance= 2ohm

Answer 2

Highest resistance can be obtained by connecting all the resistance in series:-

So,

R = 4 + 8 + 12 + 24

R (highest) = 48 ohm

Lowest resistance can be obtained by connecting all in parallel :-

So,

$\frac{1}{R} = \frac{1}{4} + \frac{1}{8} + \frac{1}{12} + \frac{1}{24} \\ \\ \frac{1}{R } = \frac{6 + 3 + 2 + 1}{24} \\ \\ \frac{1}{R} = \frac{12}{24} \\ \\ R = \frac{24}{12} \\ \\ R = 2 \: ohm$

Hope it helps.