Lesson 9.9 • NIE Practical Handbook: Experiments 35, 36, 37Interactive Simulation

Electronics Practicals Hub

Official syllabus laboratory investigations: Exp 35 (I-V characteristics of a semiconductor diode), Exp 36 (CE npn transistor transfer characteristics and current gain β), and Exp 37 (identification of logic gates from truth tables).

Marking a lesson complete represents finishing your study of the topic; it does not denote tested mastery.

Learning Objectives

Investigate diode forward/reverse conduction, plot transistor transfer characteristics to determine β, and probe digital logic IC truth tables.

Syllabus Topic Outline

NIE Practical Handbook: Experiments 35, 36, 37

1Experiment 35: Semiconductor Diode Forward & Reverse Characteristics
2Experiment 36: Common-Emitter BJT Transfer Characteristics & Current Gain (β)
3Experiment 37: Identification of Digital Logic Gates from Truth Tables

A/L Physics Laboratory: Unit 9 Electronics Practicals Hub

Official NIE A/L Physics Practical Handbook Investigations (Experiments 35, 36, 37): Semiconductor Diode I-V Characteristics, Common-Emitter BJT Characteristics, and Logic Gate Truth Table Identification.

Forward I-V Characteristics of a Semiconductor Diode (Exp 35)

Physical Principle & Governing Equations

A silicon p-n junction has a built-in barrier potential V_B ≈ 0.7 V. Negligible current flows until forward voltage reaches the knee voltage, after which current rises exponentially. Dynamic resistance is r_d = ΔV / ΔI.

r_d = ΔV / ΔI ⟹ Knee Voltage V_k ≈ 0.70 V (Silicon)

Required Laboratory Apparatus

Silicon diode (1N4007 or equivalent), variable DC power supply (0–3 V), DC milliammeter (0–100 mA), digital DC voltmeter (0–2 V), 100 Ω protective series resistor.

Experimental Observations & Data Table (Forward Bias I-V Data)

Forward Voltage V_D (V)	Forward Current I_D (mA)	Estimated Dynamic Resistance r_d (Ω)
0.20	0.00	> 1 kΩ
0.40	0.05	> 1 kΩ
0.60	0.50	400.0 Ω
0.65	2.20	29.4 Ω
0.70	8.50	7.9 Ω
0.75	25.00	3.0 Ω
0.80	60.00	1.4 Ω

Derived Experimental Result:

Barrier knee potential V_k ≈ 0.68 V. Dynamic resistance at 25 mA is r_d = 3.0 Ω.