Two resistors of resistances `200 k Omega` and `1M Omega` respectively form a potential divider with outer junctions maintained at potentials of + 3V and −15 V. Then, the potential at the junction between the resistors is-

Options

A. `+ 1 V`
B. `-0.6 V`
C. `0 V`
D. `-12 V`

Answer

C

Explanation

Potential difference across `1 Momega` resistor is-
`V_(P)-V_(B) = (18V xx 1 xx 10^(6) Omega)/((0.2 +1) xx 10^(6) Omega) = (18 V xx 1 xx 10^(6) Omega)/(1.2 xx 10^(6) Omega) = 15 V`
`V_(B) = -15 V` (Given)

`therefore V_(P)- V_(B) = 15 V` or `V_(P) = 15 V + V_(B)`
`= 15V - 15V = 0 V`
Potential difference across `200 kOmega` resistor is-
`V_(A) -V_(B) = (18V xx 0.2 xx 10^(6) Omega)/((0.2 + 1) xx 10^(6) Omega)`
`= (18V xx 0.2 xx 10^(6) Omega)/(1.2 xx 10^(6) Omega) = 3V`
`V_(A) = +3V` [Given]
`therefore V_(A) - V_(P) = 3V` or `V_(P) = V_(A) - 3V`
`= +3V - 3V = 0 V`