Electronic Devices Question 249
Question: 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 valve of V0 changes by
[Based on Roorkee 2000]
Options:
A) 0.2 V
B) 0.4 V
C) 0.6 V
D) 0.8 V
Show Answer
Answer:
Correct Answer: B
Solution:
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
Therefore Current $ i=\frac{12-0.3}{5k\Omega }=2.34mA $
Output voltage V0 = Ri = 5 kW x 2.34 mA = 11.7 V
Now consider the case when diode connection are reversed.
In this case voltage drop across the diode’s combination = 0.7 V
Therefore Current $ i=\frac{12-0.7}{5k\Omega }=2.26mA $
$ V _{0}=iR=2.26mA\times 5k\Omega =11.3V $
Hence charge in the value of V0 = 11.7 -11.3 = 0.4 V
