Presentation on theme: "Cells have positive and negative electrodes."— Presentation transcript:
1 Cells have positive and negative electrodes. Electrons build up on the negative electrode.Current is the amount of e- moving – coulombCurrent is measured in Amperes.Voltage is the difference between the potentialenergy of electrons at two point in a circuit.
5 Electrons lose energy as they move through things. Resistor: electrical device in a circuit that takes potential energy from electrons – resistance.Electrical symbol – RUnit is the ohm (Ω)The loss of potential energy over a resistor is called the “voltage drop”Schematic Symbol
6 Resistors are sometimes used to reduce the energy of a circuit for safety reasons. Any resistor that takes the energy and converts for use – load.Mechanical EnergyThermal Energy
7 e- + - e- Load a resistor that converts energy. Resistor lowers energy ●+-Loada resistor thatconverts energy.e-Resistorlowers energyremoved as heat
8 Ohm’s Law - The voltage in a wire is equal to current multiplied by resistance.
9 A bulb that has 2. 4 A flowing through it, has a resistance of 16 Ω A bulb that has 2.4 A flowing through it, has a resistance of 16 Ω. Calculate the voltage drop across the load – energy lost by the electrons to light up the bulb.e-●+-V =I · R38.4 V= (2.4 A) · (16 Ω)= 38.4 Ve-
10 A 9 V battery is hooked up to a metal wire to make a circuit A 9 V battery is hooked up to a metal wire to make a circuit. If the metal wire has a resistance of 6.5 Ω, calculate the current in the wire.e-VRI =●+-9 V6.5 Ω=e-= 1.38 A
11 V I R Voltage – Energy lost by the electrons through the circuit. Current – Number of electrons moving through the circuit.Resistance – the ability of a load or resistor to take energy.I RV