Electricity ⚡ Flashcards
Why are metals good conductors of electricity?
Metals are good conductors of electricity because they contain free electrons.
Why are insulators poor conductors of electricity?
Insulators such as plastic and rubber do not generally contain free electrons and so are poor conductors of electricity.
What are some good conductors of electricity?
Silver, copper, aluminium, steel, gold.
What are some insulators?
Rubber, plastic, glass, wood, marble.
What is electric current in a metal?
It is the flow of electrons.
What direction do the electrons flow in a circuit?
It was originally thought that the current was flowing in the opposite direction, i.e. from the positive terminal of the battery, through the conductor, to the negative terminal.
This is wrong but is still the direction of current marked on all circuit diagrams. It is called the direction of conventional current.
Electrons flow from the negative terminal through the conductor to the positive terminal.
They are repelled by the negative terminal and attracted by the positive terminal.
Why is a conductor needed in circuits?
To allow the flow of electrons.
What are the role of insulators in a circuit?
Insulators prevent the flow of electrons.
What is the role of switches in a circuit?
A switch is used to turn a circuit on (closed) and off (open).
When the switch is open, there is a break in the circuit and current stops flowing.
What is the symbol for a resistor?
—▭—
(Rectangle should be bigger).
What is the symbol of a variable resistor?
A rectangle with a diagonal arrow going through it.
What is the symbol of a switch?
Closed: a line with a circle attached to it on either side.
Example:
—⭕——⭕—
Open: the line is now diagonal to represent the break in the circuit. The line is attached to one circle now, however both circles haven’t moved.
Very bad example:
/ —⭕/ ⭕—
What is the symbol of a fuse?
A rectangle with a horizontal line through the middle.
What is the symbol of a voltmeter?
A circle with the letter V on it.
What is the symbol of an ammeter?
A circle with an A on it.
What is the symbol of a lamp?
A circle with an X through it.
What is the symbol of a cell?
——| █——
(The lines should be solid, the vertical lines should be a bit bigger).
What is the symbol of a battery?
——| █—–| █——
(All lines should be solid except the line in the middle, which should be dotted, the vertical lines should be a bit bigger).
What is cell polarity?
Batteries have a positive (+ve) terminal and a negative (-ve) terminal.
The positive terminal is represented by a long, thin line.
The negative terminal is represented by a shorter, thicker line.