Question

Diodes $D - 1$ and ${D_2}$ shown in circuit are silicon diodes. The voltage drop ($V$) across the diode ${D_2}$ and the power dissipated ($P$) by this diode (${D_2}$) are

Answer 1

First of all, we will analyze the given circuit, to look for the diode which is forward biased and the diode which is reversed biased. In a parallel connection the voltage remains the same in all the elements. However, that does not mean that current remains the same.

Complete answer:
In the given figure, we can see that the diode ${D_1}$ is forward biased and diode ${D_2}$ is reversed biased. Since the diode ${D_1}$ is biased forward the voltage drop across it is $5\,{\text{V}}$. Since the ${D_1}$ and ${{\text{D}}_2}$ diodes are linked in parallel, the voltage drop across is equal to that across ${D_1}$, i.e. $5\,{\text{V}}$.

Since ${{\text{D}}_2}$ is biased in reverse, no current flows through it and so the power dissipated by ${{\text{D}}_2}$ is zero. As we know, that power is the product of voltage and current. Since, the current is zero in reversed biased condition, hence power is also zero.

Hence, the required answer is ${V_{{D_2}}} = 5\,{\text{V}}$ and ${P_{{D_2}}} = 0\,{\text{W}}$.

Additional information:
Forward bias: The external voltage is delivered through the P-N junction diode by forward bias or biasing. The P-side of the diode is connected to the positive terminal in a forward bias configuration, and the N-side is fixed to the battery's negative side.

Diode: A diode is a semiconductor device that basically functions as a one-way current switch. It makes it possible for current to flow freely in one direction, but seriously limits current from flowing in the opposite direction.

Note: Remember that in an electric circuit, a diode (PN junction) allows current to flow more quickly in one direction than in another. Forward biasing means placing a voltage across a diode that makes it easier for current to pass, while reverse biasing means putting a voltage in the opposite direction across a diode.