The circuit contains two diodes each with a forward resistance of $50 \Omega$ and with infinite reverse resistance. If the battery voltage is 6 V , the current through the $120 \Omega$ resistance is ____ m A.

JEE Main · 2021 · 26 Feb 2021 · Shift 1 · Current Electricity

The circuit contains two diodes each with a forward resistance of

50Ω

and with infinite reverse resistance. If the battery voltage is 6 V , the current through the

120Ω

resistance is ____ m A.

Answer: 20

Solution

The two diodes point in opposite senses across the same pair of nodes, so only one of them conducts. The diode in the

100 Ω

branch is reverse biased and, having infinite reverse resistance, carries no current; that branch is effectively absent. The remaining loop has the forward resistance of the conducting diode, the

130 Ω

resistor and the

120 Ω

resistor in series across the cell:

R = 50 + 130 + 120 = 300 Ω

i = \frac{6}{300} = 0.02 A

All of this current passes through the

120 Ω

resistor, so the current in it is

20

mA.

JEE Main · 2021 · 26 Feb 2021 · Shift 1 · Integer answer

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