• 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...



In this investigation I will attempt to find the relationship between voltage and resistance in a bulb using the equation: Resistance= Voltage/Current.

Resistance: Resistance is the force that acts against charged electrons as they attempt to make their way around a circuit. More resistance means that more energy is needed to push the same number of electrons around the circuit. Many factors determine the resistance of an object for from its length or its temperature. Resistance is measured in ohms (Ω). The formula for resistance is: R=V/I

Voltage is the driving force of electrons; to measure voltage is to measure the potential difference of energy between the positive and negative terminals. Voltage is a measure of the amount of energy that you are providing per coulomb of charge therefore 1vote = 1 joule per coulomb*. Voltage is measured in Volts (V) The formula for voltage is: V= IR

Current: The current of a circuit is the rate at which the electrons flow through it. Current is measured in amps. The formula for finding current is I = Q/T where ‘Q’ is the charge passing at a certain point in the circuit measured in coulombs. Current is measured in amperes (A).

...read more.


  1. All school bags were packed away safely.
  2. While setting up the circuit the power pack was set to ‘0’ volts and unplugged.
  3. The circuit was not turned on until it was checked and approved by the teacher.
  4. The maximum operational voltage for the bulb was 6 volts; this voltage was not exceeded for safety reasons.

Apparatus: Variable Voltage Power Pack, ammeter, voltmeter, bulb, connecting leads (wires)

Method:(1)The following circuit was set up:


(2)Using the voltmeter to measure, the voltage was increased by adjusting the variable power pack from 0 to 1 volt.

(3)The reading on the ammeter changed, its new reading, at one volt was recorded

(4)Steps 2 to 3 were repeated 5 times, each time increasing the voltage by 1, up to 6 volts. Then the entire experiment was repeated twice so as to obtain 3 sets of results. Then the mean average was calculated then using the formula: Resistance= Voltage/current. The resistance in Ω (ohms) was calculated and recorded.






The voltage vs. Resistance decreasing curve graph shows a positive correlation between voltage and resistance, i.e.: as the voltage increases the resistance increases and vice versa.


...read more.


The only downside with these results was that I could only reliably calculate the resistance to the same level of accuracy as my least accurate measurement, in this case voltage, which could only be measured to one decimal place.

Therefore if I were to do this investigation again, I would change certain aspects of the method and apparatus in order to increase the accuracy and reliability.

Firstly, the reading from the voltmeter could only be taken to one decimal place, limiting the accuracy at which I could reliably state this resistance. To solve this problem I would use a voltmeter whose scale was as accurate to that of the ammeter, 3 decimal places. Preferably I would use digital volt and amp meters that would rule out any human error that might occur when using the naked eye to determining a reading.

Secondly, to increase the accuracy I would obtain more sets of results, perhaps repeat the investigation twice and find an even more accurate average current.

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

    GRAPH No2: Graph of average results... From the graph above, I can conclude that increasing the length of a wire increases its resistance. This is clearly shown where the line is straight and has a fixed gradient. As I plotted resistance against length in my graph No2, and we know

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

    This maximum temperature was maintained for about a minute, and then there was a slight decrease in temperature by approximately 1 degree, excluding the trial run, which there was a drop in temperature of four degrees.

  1. Investigation into the resistance of a filament lamp.

    I will measure the voltage to 3 significant figure, this is because if the voltage of the filament lamp was 12.04 volts then if we were measuring to 2 significant figure then the value would be 12 volts which is not very accurate so therefore it would be precise and accurate to measure the voltage to 3 significant figure.

  2. Characteristics of Ohmic and Non Ohmic Conductors.

    Since we have now discussed the conductivity of certain substances and the free electron theory, I would now like to introduce the ohmic and non ohmic conductors. Ohm's Law states that the current flowing through a certain conductor is proportional to the voltage given that physical factors such as temperature are kept under control and constant.

  1. A2 Viscosity investigation

    The stop clocks sensitivity is +or-0.05s but as it is not electronically controlled and it is based on human judgement and reaction time the actual error for this part will be greater than that stated. To reduce percentage errors comparatively greater amounts of syrup have been used as the uncertainties

  2. Characteristics of Ohmic and non-Ohmic Conductors.

    So the value of V/I increases as the current increases. Hence the resistance of the filament increases with increasing temperature. So its resistance increases with increased temperature. The resistance can be calculated by the gradient, where : Gradient = Current but Resistance= Voltage Voltage Current Therefore; Resistance = 1 Gradient As the Gradient decreases, the current increases.

  1. Investigating how temperature affects the resistance in a wire

    This means that an increase in the temperature will mean an increase in the resistance, and a decrease in the temperature will decrease the resistance. This means that the resistance is directly proportional to the temperature in the formula: Resistance ?

  2. The aim of this investigation is to find out if the length of an ...

    using Equation 2. In addition, using Equation 1, we can also predict the measurement of current (in Method 1) since we will use the same power setting on the power pack and we know the resistance of the resistor. Table 1 in the next page shows the predicted results (in italic)

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