`Ge` and `Si` diodes conduct at `0.3 V` and `0.7 V` respectively. In the following figure if `Ge` diode connection are reversed, the value of `V_(0)` changes by

Options

A. `0.2 V`
B. `0.4 V`
C. `0.6 V`
D. `0.8 V`

Answer

B

Explanation

Consider the case when `Ge` and `Si` diodes are connected as show in the given figure.
Equivalent voltage drop across the combination `Ge` and `Si` diode `=0.3 V`
`implies` Current `i=(12-0.3)/(5 k Omega)=2.34 mA`
`:.` Output voltage `V_(0)=Ri=5kOmegaxx2.34 mA=11.7V`
now consider the case when diode connection are reversed. In this case voltage drop across the diode's combination `=0.7V`
`implies` Current `i=(12-0.7)/(5 k Omega)=2.26 mA`
`:. V_(0)=iR=2.26 mAxx5 k Omega=11.3 V`
Hence charge in the value of `V_(0)=11.7-11.3=0.4 V`