Question

In Fig. shown D₁ is germanium and D₂ is a silicon diode. Knee voltage of D₁ and D₂ is 0.3 V and 0.7 V respectively. R_L = 5 K Ω . A current flows in circuit. The potential of point P is

(1) 6 V

(2) 5.7 V

(3) 5.3 V

(4) 5 V

Answer 1

(2) 5.7 V

Diode D₁ and D₂ are connected in parallel hence p.d across the two is same. The knee voltage of D₁ is 0.3V. D₁ starts conducting when p.d across it is 0.3 V under this condition diode D2 does not conduct. Due to conduction of D₁ there is a current in circuit. The p.d across load R_L = 6–0.3 = 5.7 V. This end of R_L is connected to point P, hence p.d at P = 5.7 V.