AQA GCSE HIGHER PHYSICS - Understanding Electric Charge and Current

Understanding Electric Charge and Current

What is Electric Charge?

At the heart of electricity lies electric charge, a fundamental property of matter. Think of it as a kind of "electrical energy" stored within particles. There are two types of charges:

• Positive Charge: Carried by protons, found in the nucleus of an atom.
• Negative Charge: Carried by electrons, orbiting the nucleus.

These charges exert forces on each other:

• Like charges repel: Two positive charges or two negative charges push each other away.
• Unlike charges attract: A positive charge and a negative charge pull towards each other.

What is Electric Current?

Electric current is the flow of electric charge. It occurs when charges move from one point to another within a material. Imagine a river of electrons!

The rate at which this charge flows determines the current:

• High current: A large amount of charge flows past a point in a short time.
• Low current: A small amount of charge flows past a point in a short time.

Measuring Electric Current

We use the ampere (A) as the unit for measuring electric current. The symbol for current is I.

The Equation: Q = I * t

This equation links charge, current, and time:

• Q: The total charge (in coulombs, C)
• I: The current (in amperes, A)
• t: The time (in seconds, s)

This equation tells us:

• The charge flowing past a point is equal to the current multiplied by the time.

Example: If a current of 2 A flows for 5 seconds, then the total charge that flows is:

Q = I * t = 2 A * 5 s = 10 C

Electric Current in Circuits

Circuits provide a path for electric current to flow. The key components of a circuit are:

• Power Source: Provides the energy to move charges (e.g., battery, power supply).
• Conductor: Allows the current to flow easily (e.g., wires, metal components).
• Load: Converts electrical energy into another form (e.g., light bulb, motor).
• Switch: Controls the flow of current (e.g., on/off switch).

Current flows in a circuit:

• From the positive terminal of the power source, through the load, and back to the negative terminal.

Key Concepts to Remember:

• Electric charge is a fundamental property of matter.
• Electric current is the flow of electric charge.
• The equation Q = I * t relates charge, current, and time.
• Circuits provide a path for current to flow.

Now you have a solid foundation to understand electric charge and current. Remember to practice using the equation Q = I * t to solidify your understanding!