Electric Current

This page focuses on electric current, a key concept in P4 Physics AQA and GCSE Physics Electricity revision.

Electric current is defined as the flow of charge, typically carried by electrons in metals. The page explains how current transfers energy to components in a circuit.

Definition: Electric current is the rate of flow of electric charge, measured in amperes (A).

The relationship between charge flow, current, and time is presented:

Charge flow, Q = current, I × time taken, t

The page also introduces the concept of potential difference and resistance.

Highlight: In a single closed loop, the current is the same at any point in the circuit.

Potential difference is explained as the energy transferred to a component per unit charge, measured in volts (V). The relationship between potential difference, energy transferred, and charge is given:

Potential difference, V = energy transferred, E / charge, Q

Resistance is introduced as the opposition to the flow of current in a component, measured in ohms (Ω).

Vocabulary:

• Coulomb (C): The unit of electric charge
• Ampere (A): The unit of electric current
• Volt (V): The unit of potential difference
• Ohm (Ω): The unit of electrical resistance

Current-Potential Difference Graphs

This page explores the relationship between current and potential difference, which is crucial for understanding GCSE Physics electricity exam questions and answers.

The page introduces Ohm's law, which states that for an ohmic conductor at constant temperature, the current is directly proportional to the potential difference.

Quote: "Current through a resistor at constant temperature is directly proportional to potential difference across the resistor."

The page explains how to investigate this relationship using a circuit and plot current-potential difference graphs.

Highlight: Ohm's law is a fundamental principle in electrical circuits and is often tested in GCSE Physics electricity exam questions.

The concept of ohmic conductors is introduced, where resistance remains constant as potential difference changes.

Vocabulary:

• Ohmic conductor: A conductor that obeys Ohm's law, maintaining a constant resistance as potential difference varies

This page provides essential information for students preparing for AQA Physics P4 Electric circuits exam style questions and answers.