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Wire Resistance Investigation

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Introduction

Wire Resistance Investigation Aim: To investigate how the length of a wire can affect resistance. Safety: My main concern will be that if I turn the voltage up to high the wire could snap and hot metal could fly up into the eye. So I will wear goggles to protect my eyes. Method: First I will sellotape a piece of wire over a metre long to a metre ruler. Then will connect up a battery pack to an ammeter then the ammeter to the voltmeter then the voltmeter to the piece of wire using crocodile clips at 0cm then the negative clip is moved up and down the wire stopping at 10cm, 20cm and up to 70cm. Each time the length of the wire has changed I will read the ammeter and the voltmeter and record the results so from there I can work out the resistance which is R= V/I. Other variables will be kept constant like the voltage and the thickness of the wire. The experiment will be repeated three times using the same equipment. Equipment List: 1. Ammeter 2. Voltmeter 3. Power Pack 4. Power Leads 5. Two Crocodile Clips 6. Over 1 metre of wire 7. Sellotape Fair Test: I will make this test a fair test by keeping all the variables constant. ...read more.

Middle

That if the wire increases more atoms collides with the current trying to pass through the wire so there is a resistance against the current. So therefore if the length of the wire increases the resistance increases. Also if the length of the wire was trebled or quadrupled then the resistance would also treble or quadruple. Evaluation: From my results table and my graph I can see that my results I collected are very reliable. I know this because none of my results are odd and are not out of place on the graph. During the experiment I have noticed a number of improvements that could be made. The first improvement would be the circuit. Instead of connecting the voltmeter to the circuit I would connect it to the wire that is being tested. The reason I would do this is to only measure the voltage of the wire and not the other leads of the circuit. I would also put the ammeter at the other side of the wire to only measure the current of the wire and not the other leads. To expand on the investigation I would investigate the diameter of the wire. Research All materials, solid, liquid or gases are made up of atoms. The atoms themselves consist of a central bit, called the nucleus, made up of particles called protons (which have a +ve electrical charge) ...read more.

Conclusion

simply I = V/R, and that the potential difference across a conductor equals the product of the current in the conductor and its resistance, V = IR. In a circuit in which the potential difference, or voltage, is constant, the current may be decreased by adding more resistance or increased by removing some resistance. Ohm's law may also be expressed in terms of the electromotive force, or voltage, E, of the source of electric energy, such as a battery. For example, I = E/R. With modifications, Ohm's law also applies to alternating-current circuits, in which the relation between the voltage and the current is more complicated than for direct currents. Precisely because the current is varying, besides resistance, other forms of opposition to the current arise, called reactance. The combination of resistance and reactance is called impedance, Z. When the impedance, equivalent to the ratio of voltage to current, in an alternating current circuit is constant, a common occurrence, and Ohm's law is applicable. For example, V/I = Z. With further modifications Ohm's law has been extended to the constant ratio of the magneto motive force to the magnetic flux in a magnetic circuit. Resistance values in electronic circuits vary from a few ohms, W, to values in kilohms, kW, (thousands of ohms) and megohms, MW, (millions of ohms). Electronic components designed to have particular resistance values are called resistors. ...read more.

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