Electricity Formula CheatSheet

A complete, intuitive guide for students, electricians, and curious learners

⚡ 1. Ohm’s Law

$$V=I\times R$$

Voltage is the push, current is the flow, resistance is the opposition.

What it means

If you increase the push (voltage), more current flows — unless resistance blocks it.

Analogy

Imagine water flowing through a pipe:

• Voltage = water pressure

• Current = water flow

• Resistance = narrowness of the pipe

Narrow pipe → less water flows even if pressure is high.

Explore more: Ohm’s Law

⚡ 2. Current Formula

$$I=\frac{V}{R}$$

Current increases when voltage increases or resistance decreases.

Analogy

More pressure or a wider pipe → more water flow.

Explore: Electric Current

⚡ 3. Resistance Formula

$$R=\frac{V}{I}$$

Resistance tells how much a material slows down current.

Analogy

If you know water pressure and flow, you can calculate how narrow the pipe is.

Explore: Resistance

⚡ 4. Power Formulas

$$P=V\times I,P=I^{2}R,P=\frac{V^2}{R}$$

Power is the rate of electrical work — how fast energy is used.

Analogy

Power is like how fast a car burns fuel. Higher voltage or current → more “fuel burn.”

Explore: Electrical Power

⚡ 5. Energy Formula

$$E=P\times t$$

Energy is total work done over time.

Analogy

If power is “speed of fuel burn,” energy is “total fuel burned.”

Explore: Electrical Energy

⚡ 6. AC Power (Single Phase)

$$P=V\times I\times \cos \theta$$

The term cosθ is the power factor, showing how efficiently power is used.

Analogy

Imagine pushing a box:

• If you push straight → full power

• If you push at an angle → some effort is wasted

Power factor tells how much effort is actually useful.

Explore: Power Factor

⚡ 7. AC Power (Three Phase)

$$P=\sqrt{3}\times V\times I\times \cos \theta$$

Three‑phase systems deliver more power smoothly.

Analogy

Three people pushing a cart from different angles → smoother, stronger push.

Explore: Three Phase Power

⚡ 8. Frequency

$$f=\frac{1}{T}$$

Frequency is how many cycles occur per second.

Analogy

If a fan completes 60 rotations per second → frequency = 60 Hz.

Explore: Frequency

⚡ 9. Capacitance

$$Q=C\times V$$

Capacitance tells how much charge a capacitor can store at a given voltage.

Analogy

A capacitor is like a water tank:

• Bigger tank (higher C) → stores more water (charge) at same pressure (voltage).

Explore: Capacitance

⚡ 10. Inductive Reactance

$$X_L=2\pi fL$$

Inductors resist changes in current. Higher frequency → higher reactance.

Analogy

An inductor is like a heavy door:

• Slow push → easy

• Fast push → door resists more

Explore: Inductive Reactance

⚡ 11. Capacitive Reactance

$$X_C=\frac{1}{2\pi fC}$$

Capacitors resist changes in voltage. Higher frequency → lower reactance.

Analogy

A capacitor is like a spring:

• Slow push → spring resists

• Fast push → spring moves easily

Explore: Capacitive Reactance

⚡ 12. Impedance

$$Z=\sqrt{R^2+X^2}$$

Impedance is the total opposition in AC circuits — combining resistance and reactance.

Analogy

Imagine walking through a forest:

• Resistance = straight path obstacles

• Reactance = obstacles that appear only when you move fast Impedance = total difficulty of the journey.

Explore: Impedance

🌟 Conclusion — Why This Cheat Sheet Matters

These formulas are the foundation of electrical engineering. They help you understand:

• How circuits behave

• How appliances consume energy

• How AC systems work

• How power is calculated

• How real‑world electrical systems are designed

With analogies, each formula becomes intuitive, not just mathematical.

If you want, I can turn this blog into a chapter‑style PDF, or expand it with diagrams for each formula.