Diodes & transistors worksheet with answers

Free printable Diodes & transistors worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
+−Vs​6 VR = 2.2 kΩD1​D2​I = ?

A 6 V DC source drives current through a 2.2 kΩ resistor in series with two forward-biased silicon diodes. Use the constant-drop model with 0.7 V per conducting diode. Find the current I in mA.

Vs = 6 VR = 2.2 kΩVD = 0.7 V
I = mA
2.Easy
+−Vs​6 VR1​ = 2.2 kΩR2​ = 3.3 kΩID​ = ?

A 6 V DC source is connected through resistor R₁ = 2.2 kΩ to a node X. From node X to the source’s negative terminal there are two parallel paths: resistor R₂ = 3.3 kΩ, and a silicon diode with its anode at X. Use the constant-drop model with 0.7 V. Find the diode current ID in mA.

Vs = 6 VR1 = 2.2 kΩR2 = 3.3 kΩVD = 0.7 V
ID = mA
3.Medium
RC​ = 1.2 kΩβ = 80IC​ = ?VCC​ = 10 VRB​ = 390 kΩ

An NPN transistor with β = 80 is biased by a base resistor RB = 390 kΩ from the supply VCC = 10 V. The collector resistor is RC = 1.2 kΩ and the emitter is grounded. Take VBE = 0.7 V and assume the transistor is in the active region. Find the collector current IC in mA.

VCC = 10 VRB = 390 kΩRC = 1.2 kΩβ = 80VBE = 0.7 V
IC = mA
4.Medium
RC​ = 1 kΩβ = 100VCC​ = 15 VRB​ = 470 kΩ

An NPN transistor with β = 100 is biased by a base resistor RB = 470 kΩ from the supply VCC = 15 V. The collector resistor is RC = 1 kΩ and the emitter is grounded. Take VBE = 0.7 V and assume the transistor is in the active region. Find the collector–emitter voltage VCE.

VCC = 15 VRB = 470 kΩRC = 1 kΩβ = 100VBE = 0.7 V
VCE = V
5.Hard
RC​ = 330 Ωβ = 100IC​ = ?VCC​ = 9 V5 VRB​ = 2.2 kΩ

An NPN transistor with β = 100 switches a 330 Ω load resistor connected between VCC = 9 V and its collector. The emitter is grounded. The base is driven from a 5 V logic output through a base resistor RB = 2.2 kΩ. Take VBE = 0.7 V and VCE(sat) = 0.2 V. Find the collector current IC in mA when the input is high. Decide first whether the transistor is saturated.

VCC = 9 VRC = 330 Ωβ = 100Vin = 5 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 2.2 kΩ
IC = mA
6.Hard
RC​ = 330 Ωβ = 200VCC​ = 5 V5 VRB​ = ?

An NPN transistor with β = 200 switches a 330 Ω load resistor connected between VCC = 5 V and its collector. The emitter is grounded. The base is driven from a 5 V logic output through a base resistor RB. Take VBE = 0.7 V and VCE(sat) = 0.2 V. Find the largest base resistor RB, in kΩ, that still drives the transistor just into saturation.

VCC = 5 VRC = 330 Ωβ = 200Vin = 5 VVBE = 0.7 VVCE(sat) = 0.2 V
RB = kΩ

Answer key

  1. 1. I = 2.091 mA
  2. 2. ID = 2.197 mA
  3. 3. IC = 1.908 mA
  4. 4. VCE = 11.96 V
  5. 5. IC = 26.67 mA
  6. 6. RB = 59.13 kΩ

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