Section 1 — Experiment
GARRF VIRTUAL UNDERGRADUATE ENGINEERING LABORATORY
Experiment 01 — Advanced Ohm's Law & ADC Characterization
Determine and verify empirical relationships between Voltage, Current, and Resistance utilizing a virtual microcontroller acquisition platform with error propagation analysis.
V = I × R & Dout = (Vin / Vref) × 1023
Undergraduate Ohm's Law & 10-bit ADC Transfer Model
Section 2 — Objectives
🎯 Undergraduate Objectives
- Empirically validate Ohm’s Law under continuous load conditions.
- Quantize analog signals utilizing the 10-bit ATmega328P ADC architecture.
- Evaluate systematic deviations, quantization noise, and error propagation.
- Correlate mathematical calculations with hardware serial monitor telemetry.
Section 3 — Theory
📐 Advanced Theory & ADC Formulation
For a linear resistive load with fixed $R = 220\,\Omega$:
I = Vmeasured / R
Where Vmeasured = Dout × (Vref / 1023)
Thermal coefficient tolerances and source loading impedance are factored into precision trials.
Section 4 — Virtual Circuit
🔧 Hardware Architecture
🔵
Arduino UNO
Arduino UNO
🎛️
Potentiometer
Potentiometer
💡
LED
LED
Ω
220 Ω
220 Ω
🔌
5 V REF
5 V REF
⏚
GND
GND
The potentiometer provides a variable analog voltage routed to ADC Pin A0 for real-time sampling and serial transmission.
Section 5 — Choose Controller
🧩 Choose the Virtual Controller
Arduino UNO
EXP01 Simulation
Arduino Mega
Future version
ESP32
RP Pico
Selected Controller: Arduino UNO
Section 6 — Experimental Procedure
🧪 Experimental Procedure
RECOMMENDED LABORATORY WORKFLOW
Follow the sequential steps below while interacting with the external Wokwi simulation module. Chamundi will guide you step-by-step.
Follow the sequential steps below while interacting with the external Wokwi simulation module. Chamundi will guide you step-by-step.
1Examine the virtual circuit topology and verify pin connections.
2Launch the Wokwi simulation environment via the green execution control.
3Vary the potentiometer input slowly across 5 discrete voltage tiers.
4Monitor digital counts ($D_{\text{out}}$) and voltage output via the Serial Monitor.
5Record empirical values into the undergraduate observation table.
6Compute current using theoretical formulas and compare differences.
7Analyze potential quantization errors and thermal drift components.
8Complete the final student evaluation record.
Section 7 — Enter External Simulation Tool
🚀 Enter External Simulation Tool
Arduino UNO
Click below to open the external Wokwi simulation workspace.
▶ OPEN SIMULATION WORKSPACEEXP01 • ATmega328P • Wokwi Real-Time Telemetry
Section 8 — Circuit Concept
🔌 Signal Path Schematic
Signal routing path:
- Potentiometer wiper → Analog Pin A0
- ATmega328P ADC → Quantized Counts ($D_{\text{out}}$)
- Mathematical mapping → Voltage & Current
- Series Load → $220\,\Omega$ Resistor & Indicator LED
- Console Output → USB Serial Monitor Stream
+5 V (VCC)
│
┌──────────┐
│ POT │
└────┬─────┘
│ SIG (Analog)
A0
│
┌──────▼──────┐
│ ARDUINO │
└──────┬──────┘
Pin 13
│
LED
│
220 Ω
│
GND
Section 9 — Calculator
🧮 Ohm's Law & ADC Calculator
Current = 11.373 mA | ADC Count = 512
Section 10 — Observation Table
📊 Undergraduate Observation & Error Matrix
| Trial | ADC Count ($D_{\text{out}}$) | Measured Voltage $V$ (V) | Resistance $R$ ($\Omega$) | Calculated Current $I_{\text{calc}}$ (mA) | Observed Current $I_{\text{obs}}$ (mA) | Absolute Error ($\Delta I$) |
|---|---|---|---|---|---|---|
| 1 | — | — | ||||
| 2 | — | — | ||||
| 3 | — | — | ||||
| 4 | — | — | ||||
| 5 | — | — |
Section 11 — CHITTI
CHITTI
GARRF AI Engineering Mentor
Need deep technical clarification on ADC quantization, circuit loading, or error propagation?
Ask CHITTI directly.
🤖 ASK CHITTI MENTOROpens the dedicated GARRF engineering mentor instance.
Section 12 — Engineering Challenge
🧠 Advanced Engineering Viva Questions
1. Quantization Resolution: Given a 10-bit ADC with $V_{\text{ref}} = 5.0\,\text{V}$, what is the theoretical voltage resolution step size?
Resolution = 5.0 V / 1023 ≈ 4.88 mV per ADC count level.
2. Source Impedance: Why must the driving source impedance of the potentiometer be substantially lower than the ADC input impedance?
To prevent voltage divider loading errors and current leakage into the sample-and-hold capacitor of the microcontroller ADC pin.
3. Thermal Drift: If continuous high current causes resistor temperature to rise, how does the temperature coefficient of resistance ($\alpha$) impact measured current?
Resistance increases slightly with temperature ($\Delta R = R_0 \alpha \Delta T$), resulting in a minor reduction in current for a fixed voltage.
4. Error Propagation: How do resistor tolerance margins ($\pm 5\%$) affect the overall uncertainty of the computed current?
Uncertainty propagates directly; the relative error in current equals the quadrature sum of voltage measurement error and resistance tolerance limits.
Section 13 — Student Record
📝 Student Laboratory Record
Section 14 — Completion
🧪 Experiment 01 Undergraduate Edition Complete
You have successfully completed the advanced undergraduate experimental module in the GARRF Virtual Engineering Laboratory.
LEARN • BUILD • EXPERIMENT • ANALYZE • INNOVATE
📞
CHAMUNDI — AI TEACHERUndergraduate Lab • 16 Indian Languages
Chamundi
Namaste! Let us start Experiment 01. Choose your teaching style and language below.
CURRENT VIEW: Section 1 — Experiment
Ready. Select language/style and press Start Lesson.