



A diode is reverse biased when the potential at the cathode (n-side) is higher than the potential at the anode (p-side).
(1) The potential at the anode is -12V, and the potential at the cathode is -5V. Since -12V<-5V, the diode is forward biased.
(2) The potential at the anode is 0V, and the potential at the cathode is -10V. Since 0V>-10V, the diode is forward biased.
(3) The potential at the anode is 0V, and the potential at the cathode is +5V. Since 0V<+5V, the diode is reverse biased.
(4) The potential at the anode is +5V, and the potential at the cathode is +10V. Since +5V<+10V, the diode is forward biased. Therefore, the diode in option (3) is reverse biased.
The graph shows the variation of current with voltage for a p-n junction diode. Estimate the dynamic resistance of the diode at \( V = -0.6 \) V.

If the roots of $\sqrt{\frac{1 - y}{y}} + \sqrt{\frac{y}{1 - y}} = \frac{5}{2}$ are $\alpha$ and $\beta$ ($\beta > \alpha$) and the equation $(\alpha + \beta)x^4 - 25\alpha \beta x^2 + (\gamma + \beta - \alpha) = 0$ has real roots, then a possible value of $y$ is: