Presentation on theme: "Week 2 Electricity and circuits. For centuries people have used the energy of flowing water to help them do work. What are the limitations of using water."— Presentation transcript:
Voltage (E) is the Electromotive force that makes the electrons move. Voltage is measured in volts (V) and the measurement is made by comparing one point to another reference point..
It helps to understand electricity if we compare it to flow of water. Energy can be stored in water by pumping it up to a higher elevation.
Gravity is the force exerted on the water trying to pull it back down to its original level.
The higher the water is held above its original level the more potential energy that is stored in the water.
Voltage is the difference between the 2 points. Voltage is sometimes referred to as the potential difference.
The battery serves as the pump. The push comes from the negative end (pole).
A voltmeter is used to measure the voltage in a circuit.
All materials exhibit some resistance to the flow of its electrons. This property is called resistance (R) and is measured in ohms ( ) Materials with little resistance are conductors (metals) Materials that prevent the flow of electrons are insulators (glass, plastics, ceramics, nonmetals)
What is the name for the flow of electrons in an electric circuit? Current
In what unit is electrical current measured? Amperes
What do we call materials that offer little resistance to the flow of electrons? Conductors
What instrument is used to measure the flow of current in an electrical circuit? Ammeter
What term is used to describe opposition to current flow in ordinary conductors such as wires? Resistance
Give an example of a material that is a good electrical insulator. Glass/ plastic/ non-metals
What instrument is used to measure Electromotive Force (EMF) between two points such as the poles of a battery? Voltmeter
George Ohm discovered the relationship between voltage, current and resistance in a circuit. Ohm’s Law The more resistance in a material, then the less current will flow in response to the voltage. IR V This diagram can help you Remember Ohm’s Law.