What is the equation for electrical power?
P = I x V
What is the equation for electrical energy?
E = P x t
What is a fuse used for and how does it work?
Its a safety device. If the current is too high it melts the wire in the fuse and breaks the circuit.
How does an Earth wire work?
If a live wire works loose and it comes into contact with the metal case of the appliance, the Earth wire prevents electrocution by carrying the current to the ground.
How is static charge used in an inkjet printer?
The ink droplets are given a static charge which allows them to be directed to particular places on the paper by deflecting them between charged plates.
How is static charge used in spray painting?
The tiny droplets of paint are given a static charge and the object to be painted (eg a car) is given the opposite charge. This causes the paint droplets to be attracted to the object.
What are the advantages of using static charge in spray painting?
1) The amount of paint wasted is reduced
2) A more even finish is obtained
What is the relationship between voltage, current and resistance?
V = I x R (voltage = current x resistance)
Define current
The rate of flow of charge
What device is used to measure potential difference?
Voltmeter
What is a series circuit?
An electrical circuit with only one possible path for the flow of current
What is a parallel circuit?
An electrical circuit with more than one possible path for the flow of current
What device is used to measure current?
An ammeter
What are the units of resistance?
Ohms
What is a thermistor?
A resistor in which the size of the resistance is determined by it’s temperature.
What is a non-Ohmic resistor?
A material in which voltage is not proportional to the current.
