Science Chapter 11

A closed path along which electrons that are powered by an energy source can flow

• A source of energy that generates an electric current by chemical reactions involving two different metals or metal compounds separated by a solution that is a conductor.
• e.g. AA Battery

A connection of two or more cells

• One of two metal terminals in a cell or battery
• The breakdown of an electrode is one factor that can limit the life of a cell

A solution or paste that conducts charge

A cell that contains an electrolyte that is a paste

A cell that contains a liquid electrolyte

• A cell that can be used only once
• e.g. batteries

• A cell that can be recharged
• e.g. phones

• A cell that generates electricity through the chemical reactions of fuel which is stored outside the cell
• Hydrogen fuel cell combines hydrogen that is stored in a tank or cartridge with oxygen from the air

• A cell that converts sunlight into electrical energy
• e.g. calculator

A position on a cell that must be connected to other components to form a circuit.

A control device that can complete or break the circuit it is connected to.

• A circuit with a gap within it
• Electrons do not flow through any part in the circuit where there is a gap or break

• The rate of movement of electric charge
• Current is due to the flow of electrons

• The unit of electric charge
• One coulomb is the quantity of charge that is equal to the charge of 6.25 x 10 to the power of 18 electrons.

• The unit of electric current is the ampere (A)
• 1 A in a circuit means 1 C of charge passes a given point in a circuit every second
• Measured using an ammeter

• A property of a substance that hinders electric current and converts electric energy to other forms of energy
• Occurs when electrons collide with ions or other electrons in a solid
• Resistors are devices used in a circuit to decrease the current
• Metals have a lower resistance then non metals, which is why there used as conductors in a circuit

A device used in an electric circuit to decrease the current through a component by a specific amount.

A device that transforms electrical energy into heat, motion, sound or light

• The difference between the electric potential energy per unit of charge at two points in a circuit
• The amount of work that is done on each coulomb of charge that moves between terminals of the cell
• Measured in volts (V) using a voltmeter

The unit for potential difference

A diagram that uses standard symbols to represent the components in a circuit and their connections

A circuit where there is only one path for electrons to flow

A circuit where there is more than one path for electrons to flow

• The ratio of potential difference to current is a constant called resistance
• V=IR
• I=V/R
• R=V/I

The unit for resistance

• A material in which electrons can flow with no resistance
• e.g. mercury

Does not obey or follow ohm's law

• Current: Same at all points
• Potential Difference: Split up between loads
• Resistance: More loads - greater resistance

• Current: Will split up because there is more than one path for electrons
• Potential Difference: Same down each path, because energy is not lost
• Resistance: More loads in parallel means less resistance because more paths are more convenient for electrons to flow