Electric Potential difference ? Electric Potential difference (pd, V) or Voltage (V) ? ? EMF ? ? ? electromotive force

Potential difference (Voltage), is the work done or the change in Electric Potential Energy per coulomb of charge The symbol for Voltage is V and the unit is also V, note 1V = 1JC-1

The Monkey is doing Work to bring the +ve charges together The Monkey is increasing the small +ve charge’s potential energy How much work does the monkey do in bring a 1C charge from the 1st to 5th line? How much work does the monkey do in bring a 1C charge from the 2nd to 4th line?

Equipotential surfaces ?????

Potential V is the analog of height/level/altitude/elevation h.

Electric Potential, V Is the potential energy per unit charge. Units ~ J/C E q x a b Electrical Potential can also be described by the terms; potential difference, voltage, potential drop, potential rise, electromotive force, and EMF

It takes 6 Joules of work to move 2 coulombs of charge between 2 points in an electric field. What is the electric potential difference (voltage) between these 2 points?

Pumps the charge from – to + terminal Roll of the Battery: Supplies energy Pumps the charge from – to + terminal Maintains a ΔV across the external circuit

If a battery cell provides 3 If a battery cell provides 3.0 J of electrical potential energy in moving 2 coulombs of charge through the cell, what is the potential difference (or voltage) of the cell?

Batteries provide potential difference between one end of the circuit and the other. This difference in potential makes charges move. The flow of charges is from high electric potential to low electric potential.

Charges can “lose” potential energy by moving from a location at high potential (voltage) to a location at low potential. Charges will continue to move as long as the potential difference (voltage) is maintained.

Cells – Fixed Voltage A cell is a fixed-voltage device. It has its voltage written on it. The cell will always give the same number of joules to each coulomb coming through. A 5 V battery will always give 5 J to every coulomb of electrons. Somehow it is always able to keep up. Even if the coulombs are coming through thick and fast (high current), it will still manage to give 5 J to every coulomb passing through.

Examples of cells/batteries Examples of cells/batteries. You can see the voltages written on them (from left): 3 V, 6 V, 24 V.

A fairly good model of energy in a circuit, although it has its flaws (higher-level students may like to discuss these). Note that despite having given all their energy to the bulb, the electrons are still able to travel just as fast afterwards on their way back to the battery. All of this is a bit of a fudge, but avoids having to talk about energy from electromagnetic fields etc…

V The voltage is (-)1 V. 1 J 1 J 1 J This bulb is taking 1 J from every coulomb of electrons passing through. The voltage is (-)1 V.

Conservation of Energy All the joules given by the battery to the electrons are exactly used up by the time the electrons get back to the battery. Question: You’ve already seen that you can get different currents with the same battery, depending on what you connect to it. What difference will the size of the current make to the lifetime of the battery? The higher the current, the sooner the battery will run out, since it has to give a fixed amount of energy to each coulomb of charge passing through.

The Potential Difference between their feet is zero! (0 voltage) Why aren’t birds on power lines shocked? The Potential Difference between their feet is zero! (0 voltage)