# Investigating Electricity.

GNVQ Science Unit 1 and 3

## Section A: Voltage, Current and Resistance and Ohm’s Rule

Firstly, to being this assignment I will be introducing what exactly Ohm’s rule is and what voltage, current, and resistance is and how they are measured.

• Resistance: - resistance is a measure of the degree to which an electrical component opposes the passage of current. It is the ratio of the potential difference (i.e. voltage) across an electric component (such as a resistor) to the current passing through that component: R is the resistance of the component. If the resistance of a material is low then charges can pass through it easily.

(Resistance = Voltage ÷ Current)

• Current: - Electric current is the rate of charge flow past a given point in an electric circuit, measured in coulombs/seconds which is named amperes. In most DC electric circuits, it can be assumed that the resistance to current flow is a constant so that the current in the circuit is related to voltage and resistance by Ohm’s law.

(Current = Number of Coulombs per second) & (Unit of current = Amps)

• Voltage: - Voltage is a measure of the energy required to move a charge from one point to another. A difference in the amount of electric charge between two points creates a difference in potential energy, measured in "volts," which causes electrons to flow from an area with more electrons to an area with fewer, producing an electric current.

(Voltage = Joules per Coulomb = Volts)

• Ohm’s Rule: - Ohm's law, named after its discoverer Georg Simon Ohm, states that the potential difference (or voltage drop V) between the ends of a conductor (for example, a resistor R) and the current, (I) flowing through R are proportional at a given temperature: where V is the voltage and I is the current; the equation yields the proportionality constant R, which is the electrical resistance of the device.

Aim: My aim in this coursework will be to do some experiments

To measure electrical circuits

I will be carrying out an experiment and the following

Equipments will be needed for me to carry out this experiment:

• 1 Power Pack
• 1 Voltmeter
• 1 Bulb
• 2 Resistors
• 1 Ammeter
• 2 Wires (1 black, 1 red)

To begin the experiment you must first set up my work station/ circuit, it should look something similar to the example below:

Example:

In the experiment I will be measuring the voltage and the current; I will vary the voltage from 0 volts to 10 volts and take the current reading from the ammeter.

Some devices let a large current through them. These devices have a low resistance to the flow of current. A device with a high resistance allows less current to flow through it when the same voltage is applied. Resistors pass a certain amount of current for a given voltage. High value resistors let a small current pass, and a low value resistor allow a large current to pass. Standard resistors have their resistance clearly marked and some value showing the maximum current allowed without overheating.

I will now be carrying out my experiment with the resistor.

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