AS Physics Unit 1.9 Electric Current, Charge, P.D And E.M.F Flashcards
How would you describe the electrons in this diagram?
There is a sea of electrons drifting haphazardly between the copper atoms.
What happens when there is not applied potential difference?
There is no net flow of charge and so no current flows.
What happens when there is a potential difference applied?
There is a net drift of electrons towards the region of higher potential (towards the positive). It is this drift of electrical charge which constitutes an electric current in a metal.
What is the definition of current?
Current is defined as the rate of charge flow or transfer.
What is the equation and units for charge?
Q = I x T
This is where Q = charge flowing past a fixed point in C, I = constant current in Amps, t = time taken for charge to flow past fixed point in seconds
Describe the definition of current in words?
This tells us that a current of 1A flowing in a circuit is equal to a charge of 1C passing a fixed point on the circuit every second.
What is the charge of an electron known as?
An Electron-Volt (eV).
What is the energy of one electron-volt?
It is equal to 1.6 x 10^-19J.
What is the equation to work out the number of electrons in a wire?
No. = Q / e
This is where No. = number of electrons that flow past a fixed point, Q = the total charge of all electrons in C, e = the charge of a single electron in J.
What is the definition of electromotive force?
The Electromotive Force is the amount of energy converted into electrical energy.
What is the equation and units for electromotive force?
E = W / Q
This is where E = e.m.f in volts, W = electric energy converted in joules, Q = charge in coulombs.
What is the definition of a volt?
The volt can be defined as a joule per coulomb.
What is the definition for potential difference?
The Potential Difference between any 2 points is the work done in moving a unit positive charge between the 2 points.
What is the equation and units for energy transformed?
W = Q x V
This is where W = work done or energy transformed in J, Q = charge moved in coulombs, V = potential difference in V.
What is the definition for electrical power?
Electrical power is defined as the rate at which electrical energy is converted into other forms of energy by a circuit or component such as a resistor in a circuit.
What is the equation and units for power?
P = I x V
This is where P = power in watts, I = current in amperes, V = potential difference in volts.
