This document defines key electrical concepts: A circuit is a closed loop that carries electricity. Electric current is the flow of electrons in a circuit. Voltage provides the "push" that causes current to flow. Resistance opposes current flow. Direct current (DC) flows constantly from sources like batteries, while alternating current (AC) flows back and forth from rotating sources like generators. An open circuit breaks the loop, while a short circuit accidentally connects wires. Capacitors store electric charge, and inductors store magnetic energy. Diodes allow current to flow in one direction, LEDs emit light, and transistors can switch or amplify signals.

1. Electricity
What is Circuit?
It’s a closed loop that carries electricity.
What is electric current?
It’s the flow of electron in a circuit.
What is Voltage?
It’s the “push” that causes the current to flow.
What is Resistance?
It opposes current flow in a circuit.
What is DC?
DC means direct current. In other word, it means constant current flow. For example - a battery.
Battery provides constant voltage at the terminals and therefore, supplies constant current. Direct
current is constant because it is result of chemical reaction.
What is Ac?
AC means alternating current. In other word, it means current moves back and forth. For example –
wall socket. Alternating current alternates because we produce it from a rotating source like
generator.

2. What is open circuit?
When there is a break in the circuit it is called open circuit.
What is short circuit?
When two wires accidentally connect with each other or form a bridge between them such that the
load do not get current and there forms a closed-loop of current flow, we say that there is a short
circuit. The closed-loop of current flow heats up the circuit and causes fire.
What is Capacitor?
Capacitor is an electronic component that store electric charge and therefore forms an electric field.
It stores energy in an electric field.
What is Inductor?
It’s a coiled wire that concentrates a strong magnetic field around it. It stores energy in a magnetic
field.
What is Diode?
Doide is an electronic component that allows electric current to flow in one direction. It acts like a
one-way switch.
What is LED?
LED means Light Emitting Diode. It means it acts like a diode while emitting light.
What is Transistor?
Transistor can act as an electronic switch, on or off. In addition, it can act as an amplifier.