Question

Current through $100\Omega $ resistor is
(Given forward resistance of diode = $50\Omega $, reverse bias resistance = $\infty $ )

Answer 1

Hint Diode connected in forward bias conducts and that connected in reverse biased does not. We will use this concept to approach the solution. Further we will find total equivalent resistance of the circuit and find the required current.

Complete Step by step answer
Let ${D_1}$ ​ be the diode in series with $50\Omega $ resistance and ${D_2}$​ be the diode in series with $150\Omega $ resistance.
Diode ${D_1}$ is reverse biased and ${D_2}$ is forward biased.
Since diodes in reverse bias offer infinite resistance therefore no current flows through it. Hence all current pass-through diodes ${D_2}$ .

Now we will find equivalent resistance of circuit,
${R_{eq}} = 150\Omega + 100\Omega + {R_{{D_2}}}$
 $
  \because {R_{{D_{_2}}}} = 50\Omega \\
  \therefore {R_{eq}} = 200\Omega \\
 $
Thus, total current in the circuit is,
$
  I = \dfrac{V}{{{R_{eq}}}} \\
    \\
 $
On putting value, we get
$
  I = \dfrac{6}{{200}} \\
  I = 0.03A \\
 $

As all the resistances are in series, thus we get the current passing through the $100\Omega $ resistor as $0.03A$ .

Note In forward biasing width of depletion layer decreases hence diode offers zero resistance and acts as a short circuit and in reverse biasing width of depletion layer increases hence it offers infinite resistance and acts as an open circuit. In open circuit no current flows in the circuit.