Flashcards in Unit 1: Electric Current and Direct Current Circuits Deck (81)
What needs to happen in order to pass an electric current around a circuit?
The circuit must be complete and there must be a source of potential difference.
What is electric current?
The rate of flow of charge.
What is the current due to?
The passage of charge carriers.
What happens when a current passes through a metal?
The charge carriers are electrons and they collide with each other and the fixed positive ions in the metal.
What is conventional current?
When the direction of current goes from the positive terminal to the negative terminal. It is opposite to the flow of electrons.
What is the unit for current?
What is the unit for charge?
What is one coulomb equal to?
The charge flow in one second when the current is one ampere.
What is the symbol for charge?
Why does an insulator not conduct electricity?
Each electron is attached to an atom and cannot move away from it.
What happens to the number of charge carriers in a semiconductor as temperature increases?
The number of charge carriers also increases. The resistance therefore decreases.
What happens in an intrinsic semiconductor?
Electrons break free from the atoms of the semiconductor.
What do electrons deliver from the battery to the components?
What does the battery supply each electron with?
Electrical potential energy
What is the work done by an electron equal to?
The loss of potential energy.
What is potential difference/voltage?
The work done per unit charge.
What is the emf of a source?
The electrical energy produced per unit charge passing through the source.
What is electrical energy produced equal to?
Charge x emf
What may happen due to a source's internal resistance?
Some energy may be dissipated
What effect does an electric current passing through a component have?
A heating effect and a magnetic effect.
What is power equal to?
How do you calculate power?
What is the unit for power?
What is resistance?
A measure of the difficulty of making current pass through the component.
What is resistance caused by?
Repeated collisions between the charge carriers and the fixed positive ions in the metal.
How can you calculate resistance?
What is the unit of resistance?
How do you connect an ammeter?
How do you connect a voltmeter?