Ncert Exercises & Solutions

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

1.	\(D_1\) is forward biased and \(D_2\) is revers-biased and hence current flows from \(A\) to \(B\).
2.	\(D_2\) is forward biased and \(D_1\) is reverse-biased and hence no current flows from \(B\) to \(A\) and vice-versa.
3.	\(D_1\) and \(D_2\) are both forward-biased and hence current flows from \(A\) to \(B\).
4.	\(D_1\) and \(D_2\) 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.