Resistance of a Wire

In: Science

Submitted By ryand
Words 927
Pages 4
Background scientific knowledge

Electricity

Electricity is the movement of charge (electrons) around a circuit. The charge flows throw conductors which allow the electrons to pass through. An object which does not allow electrons to pass through is an insulator.
Conductors intended to have resistance are called resistors (symbol )

Voltage- given the symbol V, measured in volts using a voltmeter
Current- given the symbol I, measured in Amperes using an ammeter

Metallic structure diagram

Resistance

Resistance is the ability to prevent or resist the flow of electrical current. Resistance occurs in an electrical circuit because of a collision between electrons and atoms, which slows the electrons down and converts some of their KE to heat energy. Resistance is measured in Ohms (Ω).

Diagram

Arrow shows direction of electron movement through the wire.

Equation

[pic]

Factors which affect resistance

Length of wire – this is being investigated
Thickness of a wire – in a thin wire there are more possible paths for the electrons to pass through, therefore more electrons can flow through at one time, this increases the current which increases the resistance.

Material of wire - wires of different densities will block more or less electrons
Temperature - the vibration of warm molecules makes them more likely to collide with electrons, and resistance increases with temperature.

Variables

Independent- length
Dependent - Voltage, current to measure, resistance
Controlled - Temperature, material of wire, cross sectional area

Circuit diagram
Method
1. set up apparatus as shown above
2. measure out a 1m length piece of wire and connect it to the crocodile clips
3. close the switch
4. set the variable resistor so that you get a less biased result- below 0.5 amps
5. take down results from the voltmeter (V) and the…...

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