Two perfectly matched silicon transistors are connected

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Two perfectly matched silicon transistors are connected as shown in figure below. Assuming the β of the transistor to be very high and forward voltage drop in diodes to be 0·7 V, the value of current I is—

1. 0 mA
2. 3·6 mA
3. 4·3 mA
4. 5·7 mA

Correct Option: B

The given circuit

Given, β of a transistor is very high it means I_B1 = I_B2 ≈ 0,
V_BE = 0·7 V. The given circuit can be redrawn as shown below—

From figure— – I × 1 kΩ – 0·7 – 0·7 + 5 = 0

or I =	5 – 1·4
	1 kΩ

or I = 3·6 mA
Hence alternative (B) is the correct choice.