Ncert Exercises & Solutions

In the figure given below, assuming the diodes to be ideal,

1.	D₁ is forward biased and D₂ is revers-biased and hence current flows from A to B.
2.	D₂ is forward biased and D₁ is reverse-biased and hence no current flows from B to A and vice-versa.
3.	D₁ and D₂ are both forward-biased and hence current flows from A to B.
4.	D₁ and D₂ are both reverse-biased and hence no current flows from A to B and vice-versa.

(b) Hint: Biasing of the junction depends on the potential difference connected through its ends.

Step 1: Find the biasing of junction D₁and D_2.

In the given circuit, the p-side of the p-n junction D₁ is connected to lower voltage and the n-side of D₁ to higher voltage.

Thus D₁ is reverse biased.

The p-side of p-n junction D₂ is at higher potential and the n-side of D₂ is at lower potential. Therefore, D₂ is forward biased.

Step 2: Find the direction of the current.

Hence, the current flows through junction B to A.