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
+−20 V220 Ω9.1 VIR​ = ?

A 9.1 V Zener diode is fed from 20 V through a 220 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 20 VVZ = 9.1 VR = 220 Ω
IR = mA
2.Easy
+−Vs​5 VR = 330 ΩD​I = ?

A 5 V DC source drives current through a 330 Ω resistor in series with a forward-biased silicon diode. Use the constant-drop model with 0.7 V per conducting diode. Find the current I in mA.

Vs = 5 VR = 330 ΩVD = 0.7 V
I = mA
3.Medium
RC​ = 2.2 kΩβ = 50VCC​ = 12 VRB​ = 820 kΩ

An NPN transistor with β = 50 is biased by a base resistor RB = 820 kΩ from the supply VCC = 12 V. The collector resistor is RC = 2.2 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 = 12 VRB = 820 kΩRC = 2.2 kΩβ = 50VBE = 0.7 V
VCE = V
4.Medium
+−24 V150 Ω6.2 V680 ΩIZ​ = ?

A 6.2 V Zener regulator is fed from 24 V through 150 Ω and supplies a 680 Ω load. Find the Zener current IZ.

Vin = 24 VVZ = 6.2 VR = 150 ΩRL = 680 Ω
IZ = mA
5.Hard
+−≤ 23 V470 Ω9.1 V

A 9.1 V Zener regulator has a 470 Ω series resistor. The input can rise to 23 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.

Vin,max = 23 VVZ = 9.1 VR = 470 Ω
PZ,max = mW
6.Hard
RC​ = 470 Ωβ = 50IC​ = ?VCC​ = 12 V5 VRB​ = 2.2 kΩ

An NPN transistor with β = 50 switches a 470 Ω load resistor connected between VCC = 12 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 = 12 VRC = 470 Ωβ = 50Vin = 5 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 2.2 kΩ
IC = mA

Answer key

  1. 1. IR = 49.55 mA
  2. 2. I = 13.03 mA
  3. 3. VCE = 10.48 V
  4. 4. IZ = 109.5 mA
  5. 5. PZ,max = 269.1 mW
  6. 6. IC = 25.11 mA

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