Electricity Flashcards
What is double insulation in domestic appliances?
Double insulation involves insulating all wires with a plastic coating and sometimes using an insulating material for the appliance casing.
Why is double insulation important?
It reduces the chance of electric shock even if the wire becomes loose and touches the outer casing.
What is earthing in electrical appliances?
Earthing connects the metal casing of appliances to the earth wire to prevent electric shock if the live wire touches the metal casing.
Why is earthing necessary for appliances with metal casings?
It provides a low-resistance path for electricity to flow through, causing the fuse to break and preventing electric shock.
What does a fuse do in an electrical circuit?
A fuse melts when the current exceeds a safe level, preventing overheating and fires.
What are the common ratings of fuses?
Fuses commonly come in 3 A, 5 A, and 13 A ratings.
Why is it important to choose the correct fuse?
Choosing a fuse slightly higher than the appliance’s requirement prevents the fuse from blowing too easily.
What happens when a fuse blows?
It needs to be replaced because it has melted to stop the current flow, protecting the appliance.
What is a circuit breaker?
A circuit breaker is similar to a fuse but can be reset after it trips, so it doesn’t need to be replaced.
How is heat energy generated in a wire?
When electrons pass through a wire they collide with ions, causing increased vibration and heating the wire.
Which appliances use the heat generated in wires?
Appliances like kettles, toasters, and hairdryers use wires with high resistance to convert electrical energy into heat energy.
What is electric current?
Electric current is the rate of flow of electric charge, measured in Amps using an ammeter.
What is voltage?
Voltage (potential difference) is a measure of how much energy is transferred between two points in a circuit, measured in Volts using a voltmeter.
What is electrical power?
Power is the rate at which electrical energy is converted into other forms , measured in Watts.
How is power related to a washing machine?
A washing machine with higher power will convert electrical energy into kinetic energy faster than one with low power.
How do you calculate energy transferred?
Energy transferred can be calculated using the power of the appliance and the time it is used.
What is the difference between direct current (DC) and alternating current (AC)?
DC flows in one direction only , while AC constantly changes direction.
Why is alternating current (AC) used for mains electricity?
AC is more efficient for long-distance transmission than DC.
What does a DC voltage-time graph look like?
A DC voltage-time graph is a straight line because the current flows in one direction only.
What does an AC voltage-time graph look like?
An AC voltage-time graph alternates between positive and negative values because the current changes direction.
