How can the polarity of an induced voltage be determined?

The polarity of an induced voltage can be determined using Lenz's Law and the right-hand rule.

Lenz's Law states that the direction of the induced current is always such that it opposes the change in the magnetic field that produced it. This law is a consequence of the conservation of energy. If the induced current were to enhance the change in the magnetic field, it would create a perpetual motion machine, which is impossible according to the laws of physics. Therefore, the induced current must always oppose the change in the magnetic field.

The right-hand rule is a simple way to remember the direction of the induced current. If you point your right thumb in the direction of the magnetic field and curl your fingers, the direction your fingers curl is the direction of the induced current. This rule is based on the physical properties of magnetic fields and electric currents.

To determine the polarity of an induced voltage, you first need to determine the direction of the induced current. You can do this by observing the change in the magnetic field and applying Lenz's Law. If the magnetic field is increasing, the induced current will flow in a direction that creates a magnetic field opposing this increase. If the magnetic field is decreasing, the induced current will flow in a direction that creates a magnetic field opposing this decrease.

Once you have determined the direction of the induced current, you can use the right-hand rule to determine the polarity of the induced voltage. If the induced current is flowing clockwise when viewed from above, the induced voltage will have a positive polarity. If the induced current is flowing counterclockwise when viewed from above, the induced voltage will have a negative polarity.

Remember, the polarity of an induced voltage is always relative to the observer. If you change your perspective, the polarity of the induced voltage may also change. Therefore, it's important to always specify the perspective from which you are determining the polarity.