Potential difference
A The potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit. Units = volts (V). This is the voltage between two points that makes an electric current flow between them. or The potential difference across a cell, electrical supply or electrical component. It is measured in volts (V). is needed to make an electric current flow in a circuit.
Inducing a potential difference
A potential difference can be induced (created) in a An electrical conductor is a material which allows an electrical current to pass through it easily. It has a low resistance. when there is movement between the conductor and a magnetic field. This can occur in two different ways:
- a coil of wire is moved in a magnetic field
- a magnet is moved into a coil of wire
This is called The production of a potential difference (voltage) when a conductor, such as a wire, is moved through a magnetic field or exposed to a varying magnetic field. If the conductor is part of an electric circuit, an induced current will flow. and is often referred to as the When motion between a conductor and a magnetic field creates electricity, ie a magnet is moved into a coil of wire. .
The induced voltage produces an induced current if the conductor is connected in a complete circuit. As with all currents, the induced current creates a magnetic field around itself. Note that this magnetic field opposes the original change. For example, if a magnet is moved into a coil of wire, the induced magnetic field tends to repel the magnet back out of the coil. This effect occurs whether a magnet is moved into a coil, or a coil is moved around a magnet.
Factors affecting the induced potential
The direction of the induced potential difference or induced current depends on the direction of movement. The current is reversed when:
- the magnet is moved out of the coil
- the other pole of the magnet is moved into the coil
The images illustrate how this works.
Image caption, A bar magnet rests outside a wire coil connected to an ammeter showing no current
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An induced potential difference or induced current will increase if:
- the speed of movement is increased
- the magnetic field strength is increased
- the number of turns on the coil is increased