Seven resistance are connected as shown in the firgure. The equivalent resistance between `A` and `B` is

Options

A. `10//3`
B. `5//4`
C. `8//3`
D. `3//2`

Answer

C

Explanation

By applying conservation of momentum
`2(6) + 1(4) = 1v_(2) + 2v_(1), 16 = v_(2) + 2v_(1)` ….(i)
By applying newton law of collision
`1 = (v_(2) - v_(1))/(2) rArr v_(2) - v_(1) = 2` ……(ii)
`rArr v_(2) = (20)/(3), v_(1) (14)/(3)`
Impulse `=` change in momentum `= (20)/(3) -4 = (8)/(3) N-s`