Electricity and Magnetism
1. Electric Charge
Electric charge is a fundamental property of matter that causes particles to experience a force when placed in an electric field. There are two types of electric charge: positive and negative. Like charges repel each other, while opposite charges attract.
Example: Rubbing a balloon on your hair can cause the balloon to gain a negative charge. If you then bring the balloon close to your hair, the hair will be attracted to the balloon due to the opposite charges.
2. Electric Current
Electric current is the flow of electric charge through a conductor. It is measured in amperes (A) and occurs when there is a difference in electric potential (voltage) between two points. Current flows from areas of high potential to areas of low potential.
Example: In a simple circuit with a battery, the positive terminal has a higher potential than the negative terminal. Electrons flow from the negative terminal to the positive terminal, creating an electric current.
3. Electric Potential (Voltage)
Electric potential, or voltage, is the difference in electric potential energy per unit charge between two points. It is measured in volts (V) and is the driving force that causes electric current to flow in a circuit.
Example: A battery has a voltage of 1.5 volts, meaning it provides 1.5 joules of energy for every coulomb of charge that flows through the circuit.
4. Resistance
Resistance is the opposition to the flow of electric current in a conductor. It is measured in ohms (Ω) and depends on the material, length, and cross-sectional area of the conductor. Higher resistance means less current flows for a given voltage.
Example: A long, thin wire has higher resistance than a short, thick wire. If you connect both wires to the same voltage source, less current will flow through the long, thin wire.
5. Magnetism
Magnetism is a force that occurs between magnets and magnetic materials. Magnets have two poles: north and south. Like poles repel each other, while opposite poles attract. Magnetic fields are created by moving electric charges or by the alignment of magnetic domains in materials.
Example: A compass needle aligns itself with the Earth's magnetic field, pointing north. This is because the north pole of the compass is attracted to the Earth's magnetic south pole.
6. Electromagnetism
Electromagnetism is the interaction between electric currents and magnetic fields. When an electric current flows through a conductor, it creates a magnetic field around the conductor. Conversely, a changing magnetic field can induce an electric current in a conductor.
Example: In an electric motor, an electric current flowing through a coil of wire creates a magnetic field that interacts with a permanent magnet, causing the coil to rotate.