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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
+−Vs​9 VR = 330 ΩD1​D2​I = ?

A 9 V DC source drives current through a 330 Ω 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 = 9 VR = 330 ΩVD = 0.7 V
I = mA
2.Easy
+−Vs​10 VR1​ = 2.2 kΩR2​ = 1.5 kΩID​ = ?

A 10 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 = 1.5 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 = 10 VR1 = 2.2 kΩR2 = 1.5 kΩVD = 0.7 V
ID = mA
3.Medium
+−9 V100 Ω5.1 V680 ΩIZ​ = ?

A 5.1 V Zener regulator is fed from 9 V through 100 Ω and supplies a 680 Ω load. Find the Zener current IZ.

Vin = 9 VVZ = 5.1 VR = 100 ΩRL = 680 Ω
IZ = mA
4.Medium
RC​ = 2.2 kΩβ = 200RE​ = 470 ΩVCC​ = 15 VR1​ = 56 kΩR2​ = 10 kΩ

An NPN transistor with β = 200 has voltage-divider bias from VCC = 15 V: R₁ = 56 kΩ from VCC to the base and R₂ = 10 kΩ from the base to ground. The collector resistor is RC = 2.2 kΩ and the emitter resistor is RE = 470 Ω. Take VBE = 0.7 V and use the Thévenin equivalent of the divider (do not neglect the base current). Find the collector–emitter voltage VCE.

VCC = 15 VR1 = 56 kΩR2 = 10 kΩRC = 2.2 kΩRE = 470 Ωβ = 200
VCE = V
5.Hard
+−≤ 21 V100 Ω12 V

A 12 V Zener regulator has a 100 Ω series resistor. The input can rise to 21 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.

Vin,max = 21 VVZ = 12 VR = 100 Ω
PZ,max = mW
6.Hard
+−≥ 18 VR = ?3.3 V≤ 25 mA

A 3.3 V Zener regulator must supply up to 25 mA to a load. The input can drop to 18 V, and the Zener needs at least 1 mA to regulate. Find the largest series resistance Rmax that keeps it regulating.

Vin,min = 18 VVZ = 3.3 VIL,max = 25 mAIZ,min = 1 mA
Rmax = Ω

Answer key

  1. 1. I = 23.03 mA
  2. 2. ID = 3.761 mA
  3. 3. IZ = 31.5 mA
  4. 4. VCE = 6.835 V
  5. 5. PZ,max = 1080 mW
  6. 6. Rmax = 565.4 Ω

Full step-by-step solutions: practise this topic on examproblems.com.