Electricity Flashcards
1
Q
Symbol and unit for charge
A
Q, coulombs (C)
2
Q
D.C. supply definition
A
In an energy supply the current is always in the same direction in the circuit. (from a cell or battery)
3
Q
A.C. Supply definition
A
The current continually changes direction backwards and forwards. (Mains supply)
4
Q
Definition of electrical current
A
The electrical charge transferred per unit time.
5
Q
4 factors which affect the resistance if a conductor?
A
- material
- length, longer wire= greater resistance
- thickness, smaller diameter= greater resistance
- temperature- heating a wire increases resistance
6
Q
Function of a diode
A
Allows current to flow through it in one direction only
7
Q
Function of a fuse
A
Melts to break the circuit if the current is too large
8
Q
Function of a resistor
A
To set the current in circuits
9
Q
For devices with a power rating of up to 720 W a __A fuse should be used
A
3A
10
Q
For devices with a rating of over 720 W we should use a __A fuse
A
13A
