What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance

Q. What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance

 

Answer:-

Given resistances R1 =4 Ω, R2=8 Ω, R3=12Ω, and R4=24Ω.
(a) If these coils are connected in series, then the equivalent resistance will
be the highest, as R=R1+R2+R3+R4
∴ R=4+8+12+24 = 24Ω
(b) If these coils are connected in parallel, then the equivalent resistance will be the lowest, given by
a
⇒R=2 Ω
∴ 2 Ω is the lowest total resistance.