Electronic Devices Question 243
Question: In the following circuits PN-junction diodes D1, D2 and D3 are ideal for the following potential of A and B, the correct increasing order of resistance between A and B will be (i) - 10 V, - 5V (ii) - 5V, - 10 V (iii) - 4V, - 12V
Options:
A) (i) < (ii) < (iii)
B) (iii) < (ii) < (i)
C) (ii) = (iii) < (i)
D) (i) = (iii) < (ii)
Show Answer
Answer:
Correct Answer: C
Solution:
(i) VA = -10V and VB = -5V Diodes D1 and D3 are reveres biased and D2 is forward biased.
$ \Rightarrow R _{AB}=R+\frac{R}{4}+\frac{R}{4}=\frac{3}{2}R $ .
(ii) When VA = - 5V and VB = - 10V Diodes D2 is reverse biased D1 and D3 are forward biased
$ \Rightarrow R _{AB}=\frac{R}{4}+\frac{R}{2}+\frac{R}{4} $ =R.
(iii) In this case equivalent resistance between A and B is also R.
Hence (ii) = (iii) < (i).
