Resistance of Wire

Topics: Electronic engineering, Digital signal processing, Boolean logic Pages: 3 (766 words) Published: March 1, 2012
Factors Affecting The Resistance Of Wire
Aim: To investigate the factors that affect the resistance in a conductor.   The main factors that affect the resistance in a conductor are: · Length
· Temperature
· Cross sectional area
· Material
· Magnetism
The factor that we are going to change is the cross sectional area. Hypothesis: I think that the higher the cross sectional area, the lower the resistance in the conductor will be.   This is because the Resistance in a metal conductor happens because as the electrons move through the material (once a voltage has been applied) they collide with the atoms in the material and as a result lose some of their energy. The idea of resistance is simply how difficult it is for the electrons to move through a material. The more difficult it is, the more energy they lose in the material on their travels.

We define electrical resistance as the ratio of voltage to current.

The equation we use to find the resistance from the current and voltage is:

Resistance is a property of a DEVICE or a COMPONENT. like a lamp, a resistor, a thermistor, a diode and so on. Its value depends on four things. 1. What it’s made of. Metals are good conductors so have lower resistance than an insulator of the same dimensions. 2. Length – the longer, the greater resistance.

3. Area of cross section – the larger the lower.
4. Temperature (metals: higher temperature = higher resistance because the vibration of the metal lattice impedes the drift of the electrons, semiconductors:  like thermistors , resistance decreases with temperature) Variable resistors or potentiometers control the length of wire we introduce into a circuit  - the volume control on a hi-fi Thermistors have a high resistance in the cold and a low resistance in the warm. They are used in logic circuits to turn heaters on and off. LDR’s (light dependent resistors have a high resistance in the dark but a low resistance in the light. As darkness falls, they are...
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