In the following circuits, PN - junction diodes `D_(1),D_(2) and D_(3)` are ideal for the following potential of A and B, the correct increasing order of resistance between A and B will be

(i) `-10V, -5V`
(ii) `-5V, -10V`
(iii) `-4V, -12V`

Options

A. `(i)lt(ii)lt(iii)`
B. `(iii)lt(ii)lt(i)`
C. `(ii)=(iii)lt(i)`
D. `(i)=(iii)lt(ii)`

Answer

C

Explanation

(i) `V_(AB)=-10-(-5)=-5V`
`D_(2) to ON (FB), D_(1), D_(3) to (RB) (OFF)`
`R_(AB)=R+(R)/(4)+(R)/(4)=(3R)/(2)`
(ii) `V_(AB)=-5-(-10)=+5`
`D_(1),D_(3) to FB (ON), D_(2) to RB (OFF)`
`R_(AB)=(R)/(4)+(R)/(2)+(R)/(4)=R`
(iii) `V_(AB)=-4-(-12)=8V`
`R_(AB)=R`