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​9 VR1​ = 1.5 kΩR2​ = 3.3 kΩID​ = ?

A 9 V DC source is connected through resistor R₁ = 1.5 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 = 9 VR1 = 1.5 kΩR2 = 3.3 kΩVD = 0.7 V
ID = mA
2.Easy
+−20 V100 Ω12 VIR​ = ?

A 12 V Zener diode is fed from 20 V through a 100 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 20 VVZ = 12 VR = 100 Ω
IR = mA
3.Medium
+−12 V330 Ω9.1 V3300 ΩIZ​ = ?

A 9.1 V Zener regulator is fed from 12 V through 330 Ω and supplies a 3300 Ω load. Find the Zener current IZ.

Vin = 12 VVZ = 9.1 VR = 330 ΩRL = 3300 Ω
IZ = mA
4.Medium
+−24 V150 Ω9.1 V1500 ΩIZ​ = ?

A 9.1 V Zener regulator is fed from 24 V through 150 Ω and supplies a 1500 Ω load. Find the Zener current IZ.

Vin = 24 VVZ = 9.1 VR = 150 ΩRL = 1500 Ω
IZ = mA
5.Hard
RC​ = 150 Ωβ = 80IC​ = ?VCC​ = 5 V3.3 VRB​ = 33 kΩ

An NPN transistor with β = 80 switches a 150 Ω load resistor connected between VCC = 5 V and its collector. The emitter is grounded. The base is driven from a 3.3 V logic output through a base resistor RB = 33 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 = 5 VRC = 150 Ωβ = 80Vin = 3.3 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 33 kΩ
IC = mA
6.Hard
+−≤ 15 V270 Ω9.1 V

A 9.1 V Zener regulator has a 270 Ω series resistor. The input can rise to 15 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.

Vin,max = 15 VVZ = 9.1 VR = 270 Ω
PZ,max = mW

Answer key

  1. 1. ID = 5.321 mA
  2. 2. IR = 80 mA
  3. 3. IZ = 6.03 mA
  4. 4. IZ = 93.27 mA
  5. 5. IC = 6.303 mA
  6. 6. PZ,max = 198.9 mW

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