Investigation in resistance in wires
Investigating Resistance in Wires Aim In this investigation I will be looking into the theory of resistance and current in wires; this theory is called Ohms Law. By doing the experiments I will be hoping to prove Ohms law correct, and testing to see if it remains constant as the voltage, and wire lengths vary. Related Theory Resistance is measured in ohms (), resistance can be calculated by using the formula V = I × R V = voltage measured in volts (V) I = current measured in amps (A) R = resistance measured in ohms () This is the formula called Ohms Law. Ohms law is the relationship between voltage, current and resistance. For a metal conductor at a constant temperature the current is directly proportional to the voltage. This means that if the current increases the voltage will also increase in the same proportion. For example: If a cell provides a voltage of 1 volt and the circuit has a resistor of 1 ohm connected to it an ammeter would read 1 amp. If the cell was replaced with a 2 Volt cell the ammeter would read 2 Amps. Resistance is caused by electrons bumping into ions. If the length of the wire is doubled, the electrons bump into twice as many ions so there will be twice as much resistance. If the cross-sectional area of the wire doubles there will be twice as many ions and twice as many electrons bumping into them, but also twice as many electrons getting
How does the power dissipated by a light bulb vary with voltage?
How does the power dissipated by a light bulb vary with voltage? Plan Introduction For my experiment, I am going to investigate how the power dissipated by a light bulb varies with voltage. To find this out, I will need to do an experiment to test this out and repeat it another two times. Meaning of terms Current - Current is the flow of electric charge. An ammeter measures current in a circuit. Voltage - Voltage is the potential difference between two points in a circuit is the electrical energy gained or lost by 1 coulomb of charge. A voltmeter measures voltage between two points in a circuit. Resistance - If a component has resistance, it changes some of the electrical energy passing through it into another form of energy. A rheostat can increase or decrease its own resistance so in that way I can control the amount of voltage across the light bulb whilst doing the experiment. Prediction I think that as the voltage across a light bulb increases, the power dissipated by the light bulb also increases but at a greater rate. This is because as the voltage increases, the current also increases. This is because if the current is the amount of electrons flowing through a circuit at any point in a circuit and if the voltage increases then the current must increase as the electrons flowing through that point are flowing faster. Therefore, as the voltage increases, the
