An E.M.F. (electromotive force) can be induced by a combination of factors, including changes in magnetic field, area, and angle. Let's explore each of these factors in detail:

Change in Magnetic Field:
When there is a change in the magnetic field surrounding a conductor, it induces an E.M.F. according to Faraday's law of electromagnetic induction. This means that if the magnetic field strength increases or decreases, or if the conductor moves into or out of a magnetic field, an E.M.F. will be induced in the conductor.

Change in Area of Cross Section:
If the area of the cross-section of a conductor changes, it can also induce an E.M.F. This is known as the magnetic flux change. When the area of the conductor changes, the magnetic field lines passing through it also change, resulting in an induced E.M.F. This phenomenon can occur, for example, when a loop of wire is stretched or compressed, altering its cross-sectional area.

Change in Angle between Magnetic Field and Area:
The angle between the magnetic field and the area of the conductor also plays a role in inducing an E.M.F. If the angle changes, the magnetic flux passing through the conductor changes as well, resulting in an induced E.M.F. This effect is known as the flux change due to the angle change.

Combination of Factors:
In some cases, all three factors - change in magnetic field, change in area, and change in angle - may be simultaneously present and contribute to the induced E.M.F. For example, if a loop of wire is rotated within a magnetic field, all three factors will be involved in inducing an E.M.F.

In summary, an E.M.F. can be induced by a combination of factors, including changes in magnetic field, area, and angle. These factors are governed by Faraday's law of electromagnetic induction, which states that a change in magnetic field, area, or angle can induce an E.M.F. in a conductor.

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