Grade 9 Electricity Unit Review

Ammeter

Instrument used to measure current in a circuit.

Voltmeter

Measures potential difference (voltage) between two points in a circuit.

Circuit Breaker

Safety device that opens the circuit if current is too high; can be reset.

Fuse

Similar to a circuit breaker, but must be replaced once blown.

Conductor

Material where electrical charges move easily (e.g. metals).

Insulator

Material where charges do not move easily (e.g. rubber, plastic).

Load

Converts electrical energy into other forms (e.g. light, heat).

Source

Provides energy (e.g. battery, generator).

Current (I)

The flow of electric charge in a circuit.

Resistance (R)

The opposition to the flow of current.

Potential Difference (V)

The energy per unit charge, also called voltage.

Grounding

Safely directs excess charge into the Earth.

Charging by Contact

Touching a charged object to a neutral one to transfer charges.

Charging by Induction

Bringing a charged object near (not touching) to cause a redistribution of charges.

Conductivity

Indicates how easily charges move in a material.

Electroscope

Device that tests if an object is charged.

Series Circuit

One path for current to flow.

Parallel Circuit

Two or more paths for current.

Renewable Energy

Can be replaced within a human lifetime (e.g. solar, wind).

Non-renewable Energy

Cannot be replenished quickly (e.g. coal, oil).

EnerGuide Label

Shows estimated energy use of an appliance in a year.

ENERGY STAR® Label

Identifies energy-efficient products.

Ohm's Law

V = I×R

Voltage (V)

Measured in volts (V).

Power

Measured in watts (W).

How is Lightning formed?