Electricity Flashcards
What is current measured in?
Amps (A)
What is the equation for resistance?
Resistance= p.d÷ current
What is resistance?
How hard it is for the current to flow
List the three equations for power
Power= energy÷ time
Power= p.d× current
Power= current (squared)× resistance
What is power?
Energy transferred per second
Name the 3 cores, their colour and use.
•live core, brown, alternating p.d
• neutral, blue, completes circuit
•earth, yellow/green, safety
What is potential difference?
Energy transferred per unit of charge
What is potential difference measured in?
Ohms
What are the energy stores?
Gravitational potential
Electrostatic
Thermal (internal)
Magnetic
Elastic potential
Nuclear
Chemical
Kinetic
What is the national grid and how does it work?
How does it increase efficiency?
The national grid is transformers, cables and pylons.
Set up transformers increase p.d which lowers the current.
This increases efficiency as less energy is wasted by heat.
What is a fuse?
A fuse is a safety device that protects the component.
If the current gets too high, the fuse line melts and snaps. This breaks the circuit, stopping the current.
What is power measured in?
Watts
What is resistance measured in?
Volts (v)
What is the equation for current?
Current= charge÷ time
What is current?
The rate of flow of charge
Why do people get electric shocks?
•p.d between the live wire and the person, the person has zero volts.
•current will flow through the person to the ground
•the current becomes earthed
What is the equation for potential difference?
P.d= energy÷ charge
Name the energy pathways.
Radiation
Electrical work
Mechanical work
Heating
What is work done measured in?
Joules
What is the equation for work done?
Work done= force× distance
What is gravitational potential energy measured in?
Joules
What is kinetic energy measured in?
Joules
What is the equation for kinetic energy?
Kinetic energy= 1/2× mass× velocity
Elastic potential energy measured in?
Joules
What is the equation for elastic potential energy?
Elastic potential energy= 1/2× spring constant× extension
What is the equation for efficiency?
Efficiency= useful output energy÷ total input energy
How is an electrical current produced?
An electrical current is produced by spinning a magnet next to a cool of wire. An alternating current will flow if the coil is connected in a circuit.
What are the property’s of a series circuit?
•current is the same everywhere
•p.d is shared between the components
What are the properties of parallel circuits?
•current is shared among the branches
•p.d total on each branch is the same
What is a short circuit?
A short circuit is when an electrical device develops a fault which results in the live wire touching the neutral wire.
