Charge and Current Flashcards
Define Electric Current in words.
Electric Current is the rate of flow of charge passed through a fixed point
State the equation that defines electric current.
Change in charge over Change in time
One Ampere (1A) is the same as…
1 Coloumb per second
What is electrc charge?
A physical property which can either be positive or negative. Opposite charges attract whilst like charges repel.
Define Coloumb
The charge that flows past a point in one second when there is a current of 1 Amp
What is the elementary charge, e?
-1.6x10-19C
What is the relative charge of a Proton?
+1
How does an object become charged?
When electrons are transferred to or from the object
What is meant by quantised charge?
The principle that the charge of any object is an integer multiple of the elementary charge
What are the charge carriers of metal?
Electrons
How can you produce an electric current in a metal wire
By moving a metal wire throguh a magnetic field
What is conventional current?
Conventional Current is the direction the positive charge flows.
What is the name given to liquids with conduct electricity
Electrolyte
What are the charge carriers in a liquid?
Mobile electrons and ions
What are cations and anions?
Cations are ions that are positively charged. Anions are ions that are negatively charged.
What is an Cathode?
The cathode is the positive charge or oxidizing elctrode that acquires electrions from external circut and is reduced during electrochemical reactions.
What is an Anode?
An anode is the negative or reducing electrode that releases electrons to external circuts and oxidizes during electrochemical reactions.
What instrument is used to measure current?
An ammeter
What is meant by conservation of charge?
Conservation of charge is the principle that the total electric charge in an isolated system that never changes.
State Kirchoff’s first law
Kirchoff’s first law states that the current flowing into a junction are equal to the sum of the circuts out of the same junction ( I in = I out)
What is number density?
Number of partcular object or species per unit volume
What are the units of number density?
m-3 or cm-3
Describe the motion of electrons in a wire as they move towards the positive terminal of the supply.
Electrons flow from the negative terminal to the positive terminal.
Describe the motion of electrons in an unconnected wire.
The electrons will collide with each other and move in random directions.
