Resistance Investigation

Resistance Investigation

Knowledge

My prediction is correct because the more thick and shorter a wire is, the lower the resistance, this allows more current to flow but in a thin and longer wire, the resistance is too high, so heat is given off and the current is reduced. The more resistance there is in a circuit, the lower the current.

Electricity from an atom

Electricity comes from an atom. In an atom there are two types of electric charge. Electrons have a negative charge. Protons have a positive charge. When you switch on a light, the electricity flowing through the wires is actually a flow of electrons. A flow of electrons is called a current. The atoms in a metal are packed closely together. Electrons often change places between atoms in a metal. Energy such a battery can push electrons along. They are pushed from a negative charge and are attracted towards a positive.

Conductors

Metals such as coppers are used to conduct the flow of electricity. There are known as conductors and are covered with plastic insulation to make wires. A conductor is any substance or material that allows electric current to push through. Many good conductors are also good conductors of heat. Silver, copper and gold are good conductors of electricity, but copper is by far the cheapest metal of the three. Copper wires are therefore used a great deal to conduct the flow of electricity.

Resistance and resistors

Bulbs do not conduct as well as connecting wire. Scientists say that they have more resistance to electricity. Energy has to be spent in overcoming this resistance. The bulb gives off this energy as heat and light. The more resistance there is in a circuit, the lower the current. Some metals have less resistance than others. I n circuits, the connecting wires are usually made of copper because it has a low resistance.

Resistors are specially designed to provide resistance. They are used in electronic circuits so that the right amount of current is fed to different parts to make them work properly. Below, a variable resistor is being used to control the brightness of a bulb. The variable resistor contains a long coil of thin nichrome wire.

Sliding the control to the right puts more resistance into the circuit, so the bulb gets dimmer.

Heat from resistance

Whenever current flows through a resistance, heat is given off. This idea is used in the filament of a light bulb. It is also used in the heating elements in appliances such as kettles, irons and toasters. The elements normally contain lengths of nichrome wire.

Insulators

Insulators are materials, which do not let electrons flow through. Their electrons are held tightly to atoms, and are not free to move. Examples of insulators are plastics, ...