Current and Voltage
Current is the flow of electricity, and voltage is the force that pushes it.
- Electric current is the flow of electrons through a conductor, measured in amperes (A).
- Voltage is the “electric pressure” or push that makes current move, measured in volts (V).
- Analogy: water in a hose → voltage is the water pressure, current is the water flow.
- Higher voltage means stronger push; higher current means more flow.
Resistance and Ohm’s Law
Resistance slows the current, and Ohm’s Law connects all three parts of the power trio.
- Resistance is how much a material opposes the flow of current, measured in ohms (Ω).
- Good conductors (copper, silver) → low resistance;
Insulators (rubber, wood) → high resistance.
- Heat is often produced when resistance is high (like in light bulbs or toasters).
- Ohm’s Law: V = I × R
- Voltage (V) = Current (I) × Resistance (R).
- Example: If a light bulb has 2 Ω of resistance and 3 A of current, the voltage is 6 V.
Fun Facts
Here are some interesting facts about electricity:
- Super-thin microchip wires have extremely high resistance if they overheat, so computers need cooling fans.
- Alessandro Volta invented the first battery in 1800, and that’s why voltage is named after him.
- Thomas Edison preferred direct current (DC), while Nikola Tesla promoted alternating current (AC), and Tesla’s system is what we mostly use today.
- Superconductors have zero resistance—electrons flow endlessly without losing energy.
Review
Let’s quickly recap what we learned about electricity’s power trio:
- What is the flow of electrons called? Current
- What is the “push” that moves current? Voltage
- What slows down the flow of electricity? Resistance
- What formula connects voltage, current, and resistance? Ohm’s Law
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