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
+−9 V100 Ω6.2 VIR​ = ?

A 6.2 V Zener diode is fed from 9 V through a 100 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 9 VVZ = 6.2 VR = 100 Ω
IR = mA
2.Easy
+−15 V330 Ω6.2 VIR​ = ?

A 6.2 V Zener diode is fed from 15 V through a 330 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 15 VVZ = 6.2 VR = 330 Ω
IR = mA
3.Medium
RC​ = 2.2 kΩβ = 150IC​ = ?RE​ = 680 ΩVCC​ = 20 VR1​ = 33 kΩR2​ = 8.2 kΩ

An NPN transistor with β = 150 has voltage-divider bias from VCC = 20 V: R₁ = 33 kΩ from VCC to the base and R₂ = 8.2 kΩ from the base to ground. The collector resistor is RC = 2.2 kΩ and the emitter resistor is RE = 680 Ω. Take VBE = 0.7 V and use the Thévenin equivalent of the divider (do not neglect the base current). Find the collector current IC in mA.

VCC = 20 VR1 = 33 kΩR2 = 8.2 kΩRC = 2.2 kΩRE = 680 Ωβ = 150
IC = mA
4.Medium
RC​ = 2.7 kΩβ = 75IC​ = ?VCC​ = 9 VRB​ = 680 kΩ

An NPN transistor with β = 75 is biased by a base resistor RB = 680 kΩ from the supply VCC = 9 V. The collector resistor is RC = 2.7 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 = 9 VRB = 680 kΩRC = 2.7 kΩβ = 75VBE = 0.7 V
IC = mA
5.Hard
RC​ = 680 Ωβ = 100VCC​ = 9 V3.3 VRB​ = ?

An NPN transistor with β = 100 switches a 680 Ω load resistor connected between VCC = 9 V and its collector. The emitter is grounded. The base is driven from a 3.3 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 = 9 VRC = 680 Ωβ = 100Vin = 3.3 VVBE = 0.7 VVCE(sat) = 0.2 V
RB = kΩ
6.Hard
RC​ = 100 Ωβ = 150IC​ = ?VCC​ = 24 V3.3 VRB​ = 3.3 kΩ

An NPN transistor with β = 150 switches a 100 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 = 3.3 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 = 100 Ωβ = 150Vin = 3.3 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 3.3 kΩ
IC = mA

Answer key

  1. 1. IR = 28 mA
  2. 2. IR = 26.67 mA
  3. 3. IC = 4.504 mA
  4. 4. IC = 0.9154 mA
  5. 5. RB = 20.09 kΩ
  6. 6. IC = 118.2 mA

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