Find the ratio of currents as measured by ammeter in two cases when the key is open and when the key is closed :

Options

A. `9//8`
B. `10//11`
C. `8//9`
D. none of these

Answer

C

Explanation

When `K` is open
`R_("net")=3R//2`
`:. i_1=E//(3R//2)=(2E)/(3R)`
When K is closed
`R_("net")=2[(Rxx2R)/(R+2R)]=4/3R`
`:. i_2=E//(4R//3)=(3E)/(4R)`
`:. i_1/i_2=8/9`