Revise calculating current, measuring potential difference and energy transfer. Find out about charge, resistance and ohms law with BBC Bitesize. The longer the wire is, the greater its resistance. If the resistance of a feet wire is ohms, the resistance of feet of the same wire is. The Relationship Between Length, Width and Resistance of a Wire Aim: To investigate how the length and width of a wire affects the resistance of the wire.
In the image at right, the water pressure below the pipe is zero. The resistance and conductance of a wire, resistor, or other element is mostly determined by two properties: In the same way, a long, thin copper wire has higher resistance lower conductance than a short, thick copper wire.
Current, voltage and resistance
Materials are important as well. A pipe filled with hair restricts the flow of water more than a clean pipe of the same shape and size. Similarly, electrons can flow freely and easily through a copper wire, but cannot flow as easily through a steel wire of the same shape and size, and they essentially cannot flow at all through an insulator like rubberregardless of its shape.
- The relationship between the length and resistance of a wire.
- Electrical resistance and conductance
The difference between copper, steel, and rubber is related to their microscopic structure and electron configurationand is quantified by a property called resistivity. In addition to geometry and material, there are various other factors that influence resistance and conductance, such as temperature; see below.
Conductors and resistors[ edit ] A 6. An ohmmeter could be used to verify this value. Substances in which electricity can flow are called conductors. A piece of conducting material of a particular resistance meant for use in a circuit is called a resistor.
Resistance and Resistivity
Conductors are made of high- conductivity materials such as metals, in particular copper and aluminium. Resistors, on the other hand, are made of a wide variety of materials depending on factors such as the desired resistance, amount of energy that it needs to dissipate, precision, and costs. Ohm's law The current-voltage characteristics of four devices: Two resistorsa diodeand a battery. The horizontal axis is voltage dropthe vertical axis is current. Ohm's law is satisfied when the graph is a straight line through the origin.
Therefore, the two resistors are ohmic, but the diode and battery are not. For many materials, the current I through the material is proportional to the voltage V applied across it: Therefore, the resistance and conductance of objects or electronic components made of these materials is constant.Effect of length ,diameter ,area on value dubaiairporthotel.infoance
This relationship is called Ohm's lawand materials which obey it are called ohmic materials. Examples of ohmic components are wires and resistors. The current-voltage IV graph of an ohmic device consists of a straight line through the origin with positive slope.
Electrical resistance and conductance - Wikipedia
Check Your Understanding 1. Household circuits are often wired with two different widths of wires: Thus, gauge wire has a wider cross section than gauge wire. A Amp circuit used for wall receptacles should be wired using gauge wire and a Amp circuit used for lighting and fan circuits should be wired using gauge wire.
Explain the physics behind such an electrical code. See Answer A gauge wire is wider than gauge wire and thus has less resistance. The lesser resistance of gauge wire means that it can allow charge to flow through it at a greater rate - that is, allow a larger current.
Thus, gauge wire is used in circuits which are protected by Amp fuses and circuit breakers. On the other hand, the thinner gauge wire can support less current owing to its larger resistance; it is used in circuits which are protected by Amp fuses and circuit breakers. Based on the information stated in the above question, explain the risk involved in using gauge wire in a circuit that will be used to power an ampere power saw.
Thus, gauge wire can safely support a circuit that uses an appliance drawing up to 20 Amps of current. In fact, a Amp circuit is protected by a fuse or circuit breaker that will flip off when the current reaches 20 Amps.
If a gauge wire was used on the same circuit, then the breaker would allow up to 20 Amps to flow through it. It could overheat and thus lead to the risk of fire. A Amp circuit should never be wired using gauge wire.