Voltage, Current & Resistance
Welcome to Circuit Analysis!
The three fundamental quantities
Every circuit analysis comes down to three quantities: voltage (the push), current (the flow), and resistance (the opposition). Understanding these deeply is the key to circuits.
Ohm's Law Triangle
The fundamental relationship between voltage, current, and resistance
Illustration: ohms-law
The Big Three
Ohm's Law
V = IR
Voltage across a resistor equals current times resistance.
Applying Ohm's Law
Easy
A 100Ω resistor has 5V across it. What current flows through it?
1
Apply Ohm's Law
I = V/R = 5V / 100Ω = 0.05 A = 50 mA
Answer:
50 mA
Key Takeaways
Voltage = potential difference (Volts)
Current = charge flow (Amps)
Resistance = opposition (Ohms)
V = IR (Ohm's Law)