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

Question 5:

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

Solution:

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

 

⇒R=2 Ω

∴ 2 Ω is the lowest total resistance.