Question

Two resistance 122 and 22 are connected in
series and then in parallel. The ratio of the
effective resistance of series and parallel
combination of resistances is
(A)9:2
(B) 2:9
(C) 1:2
(D) 3:1​

Answer 1

Step-by-step explanation:

when resistance are connected in series

R= r1+r2

= 122+22= 144ohm

when resistance are connected in parallel

1/R= 1/r1+1/r2

= 1/122+1/22

= 144/2684

1/R= 144/2684

R= 2684/144

ratio of resistance

144:2684/144

= 144:2684/144

= 20736: 2684

= 9:2