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# To Investigate the Heating Effect of an Electric Current.

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Introduction

To Investigate the Heating Effect of an Electric Current Background Information 1 Heat can be transferred in four different ways: conduction, convection, radiation and evaporation. Conduction is best in solids and considerably weaker in liquids and gases. This transfer relies on the movement of atoms and molecules. For example, if a part of a material is hotter than another part, then the hotter part has more energy than the surrounding parts. Whenever you heat any substance there is an increased amount of motion from atoms and molecules. When you heat a gas, for example, the speed at which the atoms and molecules move around increases but when you heat a solid or even a liquid the atoms and molecules vibrate more. The atoms and molecules in the substance are therefore responsible for conduction. In a gas and liquid, conduction is poor because the atoms and molecules are further apart than in a solid where they are closely held with strong bonds. Metals such as silver, copper and aluminium are good conductors. Convection takes place only in fluids (liquids and gases). Convection currents are examples of floating and sinking. When a part of a fluid is heated and made warmer the molecules expand and rise because they are less dense than the cold parts of the fluid where the molecules sink downwards because they are more dense. ...read more.

Middle

6 The depth that the heating element is submerged in the water should be the same every time and have the same position e.g. the center for each experiment. 7 External air pressure would vary but in this experiment an airtight room is not available to use. 8 The internal resistance of the heating element as the greater the resistance the slower the rise in temperature of the water but resistance will be affected by both the current and the voltage. For my experiment, I have chosen to vary the current while keeping the all the other factors constant. It is important that the other factors are kept constant for a fair test and to show that a change in current will actually affect the rise in temperature of the water. Method Apparatus A few electrical wires Some aluminium foil 1� Beaker 1� Heating Element 1� Thermometer 2� Clamps 1� Glass rod 1� Voltmeter 1�Ammeter 1� Variable Resistor 1� Battery Pack 1� Stopwatch 1� Retort Stand 1� Balance Diagram In this experiment we are measuring the rise in temperature over a fixed amount of time, which here is 5 minutes. The heating element should be connected in series to a DC battery pack using 12V, an ammeter and a variable resistor in series with a voltmeter parallel to the heating element. ...read more.

Conclusion

These steps should be repeated up to 5A and 5 minutes for each of the current readings. Safety Precautions It is necessary to wear safety goggles to protect the eyes even though the temperature of the water will not be high enough for it to boil. The apparatus should not be placed at the end of the bench and all water should be handled carefully without spilling any on the electrical equipment and wires being used. When moving or dealing with the hot heating element after each experiment, it should consider that you hold it from the rubber end where it is not hot. Prediction I predict that as the current increases the heating effect of the heating element will increase therefore the water will rise to a higher temperature in a shorter space of time. I predict this because if there is a higher current passing through the heating element then it will heat up the water even more. If this happens then there is a larger transfer of electrical energy to heat energy taking place. This can be proven by this equation: That can be made simpler into: If we can find out how much energy the heating element gives out into the water then we are also able to find out how much heat energy is absorbed by the water using this formulae: The specific heat capacity of water is 4200 J/kg/?C (Complete Physics; Stephen Pople). ...read more.

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