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

Resistance Investigation

Extracts from this document...


Physics coursework Hypothesis-I predict that the resistance of the resistors can be found by dividing the voltage by the current through the resistor. It can be found by finding the gradient of the best-fit line on the graph of voltage against current. This will happen because the voltage and current are proportional so voltage will equal constant current. The constant term is the resistance so the resistance is voltage divided by current. The gradient on the graph can be formed by dividing the unit on the y-axis by the unit on the x-axis which will be voltage divided by current or on the filament lamp graph it will be current divided by voltage. The gradient will depend on the resistance of the resistors. Ohm's law will be followed if the graph is a straight line through the origin, so this can be used to prove Ohm's law is valid. Background Information- Current is the flow of charge. ...read more.


Copper is a good conductor and as temperature increases, the resistance of a wire increases. Voltage graphs are different like the graph of an ohmic conductor is a straight line that passes through the origin; this shows that it obeys Ohm's law. The graph of the filament lamp is a non-ohmic conductor as it is a curve and clearly does not obey Ohm's law. As more current flows, the metal filament gets hotter and so its resistance increases this means the graph gets flatter. A thermistor is used in electronics and is made of a semi-conductor substance. As more current flows, the thermistor gets hotter and so its resistance decreases so the graph gets steeper. Method - Connect a power supply to the resistor and an ammeter in series and connect a voltmeter. Measure the current at volt intervals of 0.5 up to 5 volts. The test will be kept fair by making sure the temperature is kept constant, make sure that current is measured every 0.5 volts and other ways of keeping the test fair. ...read more.


Yes the temperature is kept constant as the same wire is used. The blue resistor needs the most energy as it has the highest resistance. The Filament lamp graph is a steep curved shape. It is this shape because the voltage increases as the current does not increase as much. The filament bulb has a high resistance so the electrons are stopped often and a lot of energy is released. This causes the filament to become hot and begins to glow, releasing light. The heat then causes the resistance to increase even more because the particles are vibrating faster and will stop the electrons more often. Therefore, a higher voltage is needed to allow the same current through or a lower current will pass at the same voltage. The filament lamp does not obey ohm's law, as the voltage across the bulb is not proportional to the current. This proves that ohm's law is correct in saying voltage and current are proportional at a constant temperature as the filament bulb gets hotter and does not obey ohm's law, therefore, it is not an ohmic conductor. ...read more.

The above preview is unformatted text

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. Investigate how the temperature affects the resistance of a thermistor.

    temperature of a thermistor and the resistance across it I can conclude that my prediction was correct. A thermistor is a semi-conductor and so this means that as the temperature across it and the amount of energy being transferred into the electrons increases the resistance decreases.

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

    Results 2 had a larger value for the cooling correction than graph 3 because the maximum temperature reached was higher and therefore the temperature gradient between the block and the air was greater and therefore more heat is likely to be lost into the surroundings.

  1. Investigation into the resistance of a filament lamp.

    Zero on the Kelvin scale is considered the be absolute zero; that is, the point at which all molecular motion stops. (http://www.usatoday.com/weather/wtempcf.htm) Few ways to measure the temperature of filament lamp > You could measure the wavelength of the light emitted from the filament lamp > You could use the

  2. Characteristics of Ohmic and non-Ohmic Conductors.

    For my first experiment I will be connecting the circuit as in the diagram shown above. I will first set the Variable Resistor as at its maximum value. The variable resistor will be used to supply varying voltage to the wire.

  1. Investigating how temperature affects the resistance in a wire

    This is because, as I have explained earlier the range and the deviation of the results from the mean determines how accurate the results are. Graphs 3 and 4 show how the standard deviation and the range of the results change over the temperature range used in the experiment.

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

    31.88 80.0 2.59 0.06 43.17 90.0 2.60 0.06 43.33 The second set of results is shown in the table below: TABLE No2 Length of Wire (cm) Voltage (V) Current (A) Resistance (?) - rounded up to 2 d.p R=V/I 10.0 1.70 0.35 4.86 20.0 2.00 0.22 9.09 30.0 2.25 0.17

  1. Characteristics of Ohmic and Non Ohmic Conductors.

    The battery or cell provides an electromotive force. This force pushes the electrons into the circuit. From this perhaps we can understand that when the voltage increases, the amps also might increase. From the readings of these two components, graphs are drawn.

  2. To investigate whether the two resistors and the bulb given is an ohmic or ...

    Skill 5 Conclusions and Evaluations Conclusions To conclude from the V/I graphs, Resistor 1 (#8) has a resistance of 53.3? (?6?). Resistor 2 (#3) has a resistance of 20? (?2?). The uncertainty values here are deduced by using the min/max resistance error values, calculated from the graphs.

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