Yr 9 Physics Electricity

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What is energy?

The ability to do work or cause change.

What is electric current?

The flow of electric charge through a conductor.

What is voltage (potential difference)?

The energy per unit charge, measured in volts (V).

What is resistance?

A material’s opposition to the flow of electric current, measured in ohms (Ω).

What is EMF (Electromotive Force)?

The voltage generated by a battery or power supply when no current flows.

What is a conductor?

A material that allows electrons to flow easily.

What is an insulator?

A material that resists the flow of electric charge.

What is static electricity?

The build

What is electric power?

The rate at which electrical energy is transferred, calculated using P = IV.

Name the 9 types of energy

Kinetic, Potential, Thermal, Chemical, Electrical, Nuclear, Light, Sound, Elastic

What is kinetic energy?

Energy of a moving object.

What is potential energy?

Stored energy based on position or condition.

What is thermal energy?

Energy related to the temperature of an object.

What is chemical energy?

Energy stored in chemical bonds.

What is electrical energy?

Energy from the movement of electrons.

What is nuclear energy?

Energy stored in the nucleus of an atom.

What is light energy?

Energy that travels in waves and can be seen.

What is sound energy?

Energy carried by vibrations through a medium.

What is elastic energy?

Energy stored in stretched or compressed objects.

State the Law of Conservation of Energy

Energy cannot be created or destroyed, only transformed.

State the Law of Electrostatic Attraction

Opposite charges attract, like charges repel.

What happens when two objects are rubbed together?

Electrons are transferred, causing one object to become negatively charged and the other positively charged.

What does the Materials Interaction Table show?

Which object gains or loses electrons when rubbed together.

How will a negatively charged object move near another negative object?

It will be repelled.

How can an object become neutral?

By gaining or losing electrons to balance charge.

List 3 ways to neutralise charge

Conduction, grounding, and ionisation.

What direction do electrons flow?

From negative to positive terminals.

In diagrams, what does the direction of current represent?

Flow of positive charge (conventional current).

What is the relationship between EMF and current?

Higher EMF usually results in a higher current.

What is the relationship between resistance and current?

As resistance increases, current decreases.

List four factors that affect resistance

Length of wire, thickness, material, and temperature.

How does wire length affect resistance?

Longer wires have more resistance.

How does wire thickness affect resistance?

Thicker wires have less resistance.

What is Ohm’s Law?

V = I × R (Voltage = Current × Resistance)

What does an Ohmic resistor graph look like?

A straight line (linear).

What does a Non

Ohmic resistor graph look like?

What can a Voltage vs. Current graph be used for?

To calculate resistance (slope = resistance).

How can you find resistance from a graph?

Use the gradient: Resistance = Voltage ÷ Current

Formula for Power

P = IV

Formula for Energy

E = P × t

Formula for Power with energy and time

P = E ÷ t

What are the components of a complete circuit?

Power supply, conductor (wires), load (e.g., bulb), and switch.

What does a resistor symbol look like?

A zig

What does a cell symbol look like?

Two lines, one longer (positive) and one shorter (negative).

What does a voltmeter measure?

Voltage across a component.

What does an ammeter measure?

Current through a component.

How do you draw a complete circuit?

Include a power source, wires, and at least one load in a closed loop.

What is the purpose of a switch?

To open or close the circuit.

How is current affected in series circuits?

Current is the same through all components.

How is voltage affected in parallel circuits?

Voltage is the same across each branch.

What energy change happens in a light bulb?

Electrical energy → Light + Thermal energy

How does a light bulb work?

Electric current flows through a filament with high resistance, heating it until it glows.

What energy transformation happens in a fan?

Electrical energy → Kinetic energy

What energy transformation happens in a speaker?

Electrical energy → Sound energy