Charge Flashcards
Define Electric current
Electric current, I, is defined as the rate of flow of charge.
Charge, Q, is defined as…
1 coulomb is defined as the flow of charge in a time of 1 second when the current is 1 ampere.
The net charge of a particle is due to…
the gain or loss of electrons. In an atom, the number of
protons equals the number of electrons, so the charges cancel each other out and the overall
charge is neutral.
Electric current is
the rate of flow of charge
How can charge be carried around ?
Charge can be carried in several ways, for example by free delocalised electrons in a metal or positive and negative ions from electrolytes commonly known as ionic solutions/ionized liquids.
Cations will be attracted to the… , and the anions will be
attracted to the…. .
cathode, anode
What is Conventional current ?
Conventional current is the rate of flow of charge from the positive to the negative terminal, and this is how all electric currents are treated, regardless of the direction the charge carriers are moving in.
In metals, the electrons flow from
negative to positive, so the electron flow is in the opposite direction to the conventional current.
Kirchhoff’s first law states
for any point in an electrical circuit, the sum of the currents in to that point is equal to the sum of the currents coming out of that point. This law is a consequence of the conservation of charge.
The law of conservation of charge
Charge is a fundamental physical property, which cannot be created
or destroyed, but only conserved. Thus, the total amount of electric charge in the universe is constant.
A larger current may be due to
A greater no of electrons passing at a given point in the circuit, which may be due to a larger cross sectional area of the wire
or
The same number of electrons moving faster through the wire
emf is used to describe
when work is done on the charge carriers
emf is defined as
the energy transfered from chemical energy to electrical energy per unit charge
Define mean drift velocity
The mean drift velocity, v, is defined as the average velocity of the electrons as they travel down the wire, colliding with positive metal ions.
Describe the motion of electrons in a metal before and after it is connected to a power supply
When electrons move through a metal, they frequently collide with the positive metal ions, resulting in random movement.
When a power supply is connected, the free electrons are attracted towards the positive terminal, but they still collide with the positive metal ions.
