ELECTRIC POTENTIAL

SO THERE I WAS… WITH NOTHING BETTER TO DO THAN SIT AROUND AND THINK… Why are some sources of energy so dangerous to touch, while others are not?

ELECTRIC POTENTIAL Energy separates positive and negative charges in a battery. This explains why electrons collect at the negative terminal (cathode) and why they leave the other end of the battery positive (anode). The electrical energy stored in the battery is called the electrical potential energy.

ELECTRIC POTENTIAL Remember that electrical circuits convert electrical energy into useable energy (heat, light, sound, etc.). The amount of energy stored in a group of electrons is known as the electric potential (or voltage). The higher the electric potential of a group of electrons, the larger the electric current will be.

ELECTRIC POTENTIAL As electrons move along a circuit, they “drop off” all of their potential energy before returning to the energy source. The amount dropped off is divided evenly among the loads on the circuit.

ELECTRIC POTENTIAL Electric potential is measured in volts (V). A battery in a flashlight has an electric potential of ~ 1.5 V. A car battery has an electric potential of ~ 12 V. A voltmeter measures electric potential. The needle points to the number of volts when connected to the terminals on a power source.

POTENTIAL DIFFERENCE All forms of energy are measured in joules (J). However, when we describe the energy of an electron in a circuit, we describe the POTENTIAL ENERGY of one electron, or of one unit of charge. This relationship can be written as a formula: where V is potential difference in volts E is energy in joules Q is charge in coulombs

ELECTRIC POTENTIAL For example, in a battery, 45 J of energy are converted into electrical energy. This energy places 15 C of charge at the cathode, leaving a deficit at the anode. What is the potential difference across the battery? P: The potential difference is 3.0 V. A: G: E = 45 J Q = 15 C S: V = 45 J ÷ 15 C = 3.0 V R: V = ?

ELECTRIC POTENTIAL Voltage is shared between all of the loads in a circuit. The greater the number of loads, the less voltage each one will have. VT = V1 + V2 + V3

ELECTRIC POTENTIAL VT = V1 + V2 + V3