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
+−18 V150 Ω6.2 VIR​ = ?

A 6.2 V Zener diode is fed from 18 V through a 150 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 18 VVZ = 6.2 VR = 150 Ω
IR = mA
2.Easy
+−Vs​15 VR1​ = 680 ΩR2​ = 2.2 kΩID​ = ?

A 15 V DC source is connected through resistor R₁ = 680 Ω to a node X. From node X to the source’s negative terminal there are two parallel paths: resistor R₂ = 2.2 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 = 15 VR1 = 680 ΩR2 = 2.2 kΩVD = 0.7 V
ID = mA
3.Medium
RC​ = 1.5 kΩβ = 80RE​ = 2.2 kΩVCC​ = 18 VR1​ = 100 kΩR2​ = 22 kΩ

An NPN transistor with β = 80 has voltage-divider bias from VCC = 18 V: R₁ = 100 kΩ from VCC to the base and R₂ = 22 kΩ from the base to ground. The collector resistor is RC = 1.5 kΩ and the emitter resistor is RE = 2.2 kΩ. 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 = 18 VR1 = 100 kΩR2 = 22 kΩRC = 1.5 kΩRE = 2.2 kΩβ = 80
VCE = V
4.Medium
+−9 V220 Ω5.1 V680 ΩIZ​ = ?

A 5.1 V Zener regulator is fed from 9 V through 220 Ω and supplies a 680 Ω load. Find the Zener current IZ.

Vin = 9 VVZ = 5.1 VR = 220 ΩRL = 680 Ω
IZ = mA
5.Hard
RC​ = 150 Ωβ = 100IC​ = ?VCC​ = 24 V3.3 VRB​ = 2.2 kΩ

An NPN transistor with β = 100 switches a 150 Ω load resistor connected between VCC = 24 V and its collector. The emitter is grounded. The base is driven from a 3.3 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 = 24 VRC = 150 Ωβ = 100Vin = 3.3 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 2.2 kΩ
IC = mA
6.Hard
+−≤ 24 V150 Ω9.1 V

A 9.1 V Zener regulator has a 150 Ω series resistor. The input can rise to 24 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.

Vin,max = 24 VVZ = 9.1 VR = 150 Ω
PZ,max = mW

Answer key

  1. 1. IR = 78.67 mA
  2. 2. ID = 20.71 mA
  3. 3. VCE = 14.13 V
  4. 4. IZ = 10.23 mA
  5. 5. IC = 118.2 mA
  6. 6. PZ,max = 903.9 mW

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