Potential Difference Flashcards
what does a cell actually produce
an electromotive force
what does an electromotive force create
a potential difference in a circuit
what does this potential difference in the circuit do
- the charge carriers in the circuit components and connecting wires experience a force
- causing the charges to move around the circuit
why does the presence of potential difference directly lead to there being power in the circuit
- because the potential difference is doing work on the charges
- and if its doing work energy is being transferred
- as this is happening as time passes, the rate of work done or energy transferred can be calculated
- which is what power is
there is a reservoir of water attached to a paddle wheel in a cylinder which has a pipe going into a sink. the reservoir is above the paddle wheel and a tap is in between them. what is different between the reservoir and the pipe connecting the pieces
- the pressure difference in the reservoir is much larger than in the pipes
- as the reservoir is holding the weight of water
- whereas the pipes arent
what happens when the tap is opened and what is it caused by
- the water flows down the pipe and turns the paddle wheel
- this is because of the pressure difference
what is the energy transfer taking place when the tap is opened
- the gravitational potential energy of the water is being transferred to its kinetic energy stores as it flows down
- then that is transferred to the kinetic energy stores of the paddle
- causing it to rotate
in an actual circuit, what is happening in the cell which cause it to produce an electromotive force
- a chemical reaction
- this is what gives rise to the electrical potential difference across the cell terminals
if there is a switch in the circuit which is open, would the electrons still feel a force from the electrical potential difference created by the cell
- yes
- because its existence exerts a force on the electrons either way
- its just that the electrons arent moving as the circuit isnt complete
what does it mean if the electrons arent moving even though a force is being exerted on them
- work isnt being done on the electrons
- as work = force x distance and there is no distance being traveled
- which correctly implies that there is no power in the circuit
what happens when the switch is closed
- the electrons experiencing the force begin to move around the circuit
- now that they are moving work is being done on them
why does the temperature of the filament lamp begin to rise in terms of energy transfers
- the chemical potential energy stored in the cell is converted to vibrational kinetic energy of the atoms in the filament of the lamp
- this vibration releases thermal energy
- causing the temperature to rise
what is the basis of the definition of potential difference
that electrical energy in a circuit can be converted into other types of energies
what are the energy transfers for light to be produced in a circuit and for a motor to work
- electrical energy is transferred to the kinetic and thermal energy stores of a filament lamp, producing light
- and electrical energy is powering a motor by transferring its energy to its kinetic energy stores
using the basis of the definition of p.d. what would the potential difference between two points in a circuit be called
- the electrical energy per unit charge
- converted into other forms of energy