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To measure resistance and verify ohms law

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AIM-To measure resistance and verify ohms law


Current is the rate of flow of charge. Electrons carry the charge, which they get from the battery around a circuit. Current flows from negative to positive, even though we usually say it flows from positive to negative, as this is conventional current.

There are two types of circuit: - Series circuit.

     - Parallel circuit

A series circuit is when the electrons have only one choice of path. This circuit can have an infinite number of components as long as they are all in series. However if bulbs are included in this circuit, then the voltage is shared between them.

In parallel circuits the electrons have more than one choice of path. The current is shared in parallel circuits but the voltage stays the same.

The current is measured in amp’s (A) by an ammeter. How much energy each electron has gained from the battery, is known as voltage. Voltage is measured in volt’s (V) by a voltmeter. When voltage increases, current also increases. This is because the electrons are given more energy so they will be able to flow through the wire faster.

A resistor controls the current. There are two types of resistor:

  • Fixed and
  • Variable

A fixed resistor cannot change its value. However a variable resistor can, it is used in remote controls to alter the volume.

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Potential Difference (Voltage) and Current Measurement for a Filament Bulb.

Claremont High School Physics Department.


                                        CURRENT (A)



Black Resistor

Red Resistor

Blue Resistor

Test 1

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The anomalous results that I have obtained could be the result of inaccurate or faulty equipment. Another reason could be that the meters were analogue meters and therefore had to be read by the human eye so mistakes in the accuracy of the readings could have easily occurred. There could have been a slight temperature increase as the power pack heated up. The blue resistor had a few results, which did not fit in a straight line. As it was the last resistor to be tested the wire could have heated up during the course of the experiment, making the readings less accurate.

To improve the experiment digital meters could have been used to avoid inaccurate readings by the human eye. Also the wire could be given time to cool down in between each test so inaccurate results could be avoided.

Sources of Information

* CD- ROM - Encarta 2000

* SPG GCSE Double Science Physics Revision Guide

  2001 Edition

* Potential Difference (Voltage) and Current Measurement for a Filament Bulb.

Claremont High School Physics Department.

...read more.

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