• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Factors Affecting The Heating Effect Of A Current.

Extracts from this document...


Question: Factors Affecting The Heating Effect Of A Current.

Planning Stage


        “Electricity can produce for effects:

HEAT: Hairdryers/kettles, LIGHT: light bulbs, SOUND: speakers, MOTION: motors.

All resistors produce heat when a current flows through them. Whenever a current flows through anything with electrical resistance then electrical energy is converted into heat energy. The more current that flows, the more heat is produced. Also, a bigger voltage means more heating, because it pushes more current through. However, the higher you make the resistance, the less heat is produced. This is because a higher resistance means less current will flow, and that reduces the heating. The amount of heat produced can be measured by putting a resistor in a known amount of water or inside a solid block and measuring the increase in temperature.” (Parsons, 2000)            

“Current flow is accompanied by the transfer of electrical energy and it is often necessary to know the rate at which a device brings about this transfer. The power of a device is the rate at which it transfers energy. If the p.d. across a device is V and the current through it is I, the electrical energy W transferred from it in time t is     W = ItV

The power P of the device will be     P = W     = ItV

                                                                         t         t

                                                       P = IV

The unit of power is the watt (W)

...read more.


The expression P = V²/R shows that for a fixed supply p.d. of V, the rate of heat production by a resistor increases as R decreases. Now R = pl/A, therefore P = V²A/pl and so where a high rate of heat production at constant p.d. is required, as in an electric fire on the mains, the heating element should have a large cross-section area A, a small resistivity p and a short length l. It must also be able to withstand high temperatures without oxidizing in air (and becoming brittle). Nichrome is the material that best satisfies all these requirements.

Electric lamp filaments have to operate at even higher temperatures in order to emit light. In this case, tungsten, which has a very high melting-point (3400ºC), is used either in a vacuum or more often in an inert gas (nitrogen or argon). The gas reduces evaporation of the tungsten and prevents the vapour condensing on the inside of the bulb and blackening it. In projector lamps there is a little iodine which forms tungsten iodide with the tungsten vapour and remains as vapour when the lamp is working, thereby preventing blackening.” (Duncan, 1973)

        “An effect of electrical current is that it heats the wire through which it is flowing.

...read more.


To make this a fair test, between readings we will cool the thermometer down, back to the original temperature, and we will cool the heater. We will also change the water. We will also make sure we will use the same type of cup, which is polystyrene.


        Do not carry out the experiment near a sink or tap because water and electricity are dangerous when mixed. Carry out the experiment in the centre of the table, not near the edge. Bags should be put out of the way.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Electrical & Thermal Physics essays

  1. Peer reviewed

    Measurement of the resistivity of Nichrome

    5 star(s)

    Graph B (Wire B) gradient (?/cm) 0.104 0.196 cross-sectional area(mm�) 0.109 0.058 resistivity (?�m) (3s.f.) 1.13�10-6 1.14�10-6 uncertainty �4.5% �2.6% From the table above, I can get the Final Results, The resistivity for Wire A is 1.13�10-6?�m�4.5% The resistivity for Wire B is 1.14�10-6?�m�2.6% I can see find that the

  2. I am going to investigate what the resistivity is of a pencil lead. ...

    As you can see the equation of the line is 1.7984x. This figure represents the resistance of the pencil lead. As this was only the preliminary I will not need this figure. However, if this were the real experiment I would use this figure (which is also the gradient of the line)

  1. Investigating the effect of 'length' on the resistance of a wire

    * I will keep equipment away from edge of the table as it may fall on me or somebody else causing an injury. Apparatus: * Two (2) Batteries (each 1.5 V). * Crocodile clips. * Connecting Wires. * A voltmeter.

  2. The aim of my investigation is to determine the specific heat capacity of aluminium.

    These results are also shown on the graphs. For my trial run the time delay was 3 minutes, (this was performed without any oil in the hole with the thermometer.) During this time there was a temperature rise of 4 degrees.

  1. Investigation into the resistance of a filament lamp.

    Make sure that the voltmeter and the ammeter are connected into the circuit correctly. xiii. Once your circuit has been checked switch on the power supply. xiv. Check if the circuit works, and the ammeter and voltmeter is giving you write values.

  2. resistivity if a nichrome wire

    The electrons in the wire gain more kinetic energy causing them to vibrate more. This means that the collision of the electrons increase between the electrons and the ions in the wire. Therefore there is of a less chance that the electrons are being carried across the component.

  1. Physics - Resistivity

    in the bulb, so I can draw a table, find the averages, and draw a graph; this would ensure I get as much of an accurate result a possible and minimise any affects that errors would have on my result.

  2. Heating Effect of a Electrical Current

    So the less water, the temperature will increase more and vice versa. Therefore water is a factor for temperature change so must be kept constant for a fair test. Why time should be kept constant: This is because if there is more time for the heater to convert the electrical energy to heat energy, the water will heat up more.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work