Ohm's Law Lab
Explore Circuits (Series/Parallel), the Magic Triangle, and IV Graphs.
V = I × RCalculator
Ohm's Law Formulas
| Symbol | Quantity | Unit |
|---|---|---|
| V | Voltage | Volts (V) |
| I | Current | Amperes (A) |
| R | Resistance | Ohms (Ω) |
| To Find | Formula | Analogy |
|---|---|---|
| Voltage (V) | I × R | Pressure needed |
| Current (I) | V / R | Flow rate |
| Resistance (R) | V / I | Pipe width |
One Law to Rule Them All.
$V=IR$ isn't just a formula; it's the DNA of every electronic device. Whether it's a simple LED or a supercomputer, everything obeys Ohm's Law.
The River Analogy: Circuit Types
Series Circuit
The Single Stream
Imagine a river with several dams one after another.
- Current: Same everywhere. The water passing Dam 1 MUST also pass Dam 2.
- Voltage: Splits up. Each dam drops some pressure.
Parallel Circuit
The Split River
Imagine a river that forks into two branches.
- Current: Splits. Some water goes left, some goes right.
- Voltage: Same. Both branches drop the same total height (from top to bottom).
Why Houses are Parallel
Every outlet in your home is wired in Parallel. This ensures two things: 1. Every device gets the full 120V (or 230V). 2. Turning off your TV doesn't break the circuit and turn off your Fridge!
Frequently Asked Questions
What is Ohm's Law?
Ohm's Law states that Current ($I$) is directly proportional to Voltage ($V$) and inversely proportional to Resistance ($R$). $I = V / R$. This creates the famous formula $V = IR$.
Are houses wired in Series or Parallel?
Parallel. If houses were wired in Series, turning off one light would break the circuit and turn off EVERY light in your house! Parallel wiring allows each appliance to operate independently with full voltage.
What happens to Total Resistance in Parallel?
Detailed answer: Adding resistors in Parallel DECREASES total resistance. It provides more paths for electrons to flow, like opening more checkout lanes at a store. The total resistance is always less than the smallest individual resistor.
What is a Voltage Divider?
A Series circuit acts as a Voltage Divider. The total voltage splits between resistors based on their size. A larger resistor drops more voltage. Formula: $V_{out} = V_{in} \times (R_2 / (R_1 + R_2))$.
Why does a light bulb violate Ohm's Law? (Non-Ohmic)
A filament bulb is "Non-Ohmic". As it gets brighter, it gets hotter. Heat causes tungsten atoms to vibrate violently, making it harder for electrons to pass (Resistance increases). So, doubling current requires more than double voltage.
What is a Short Circuit?
A Short Circuit is a path of near-zero resistance (e.g., a wire directly across a battery). According to $I = V/R$, if $R \approx 0$, Current ($I$) becomes dangerously huge, causing sparks and fire!
How do I calculate Resistance from V and I?
Rearrange Ohm's Law: $R = V / I$. If you have 10 Volts and 2 Amps flows, the resistance must be 5 Ohms.
Is Current the same everywhere in a Series circuit?
Yes! In Series, electrons have only one path. They cannot disappear or pile up, so the flow rate (Current) is identical at every point in the loop.
Does Current split equally in Parallel?
Only if the resistors are identical. If resistors are different, electricity follows the path of least resistance. More current flows through the small resistor, and less through the large resistor.
What is the Power Formula?
Electrical Power ($P$) is $V \times I$. Can also be written as $P = I^2 R$ (useful for heat loss) or $P = V^2 / R$ (useful for parallel loads).