# How to find current in a transformer

FAQ | Feb 22,2023

Hold the transformer winding with the right hand, four fingers for the direction of the applied current, thumb for the direction in the flux.
The induced electromotive force always resizes the increase of the value of the current, so turn the hand (just up, this time down) four fingers is the direction of the induced electromotive force. (that is, in the opposite direction of the applied current)
Extend the right hand, so that the thumb is perpendicular to the other four fingers, and they are in a plane with the palm, so that the magnetic wire enters from the palm, and the thumb points to the direction of the wire movement, then the direction of the four fingers is the direction of the induced current. When the magnet is inserted into the coil, the direction of the original magnetic flux is downward, and the magnetic flux tends to increase. According to Lenz’s law, the direction of the magnetic flux established by the induced potential is opposite to that of the original magnetic flux. That is, when the new flux direction is up, use the right hand screw rule to determine the direction of the induced electromotive force, and when the magnet is pulled out of the coil, the original magnetic field direction in the coil is down. Induced electromotive force is in the phenomenon of electromagnetic induction. Since there is induced current in the closed circuit, there must also be electromotive force in the circuit. The electromotive force generated in the phenomenon of electromagnetic induction is called induced electromotive force.
Method for determining the direction of induced electromotive force in transformers
1. The reference direction of the voltage in the primary winding is consistent with that of the current.
2. The reference direction of the flux and the reference direction of the current conform to the right hair screw rule,
3. The reference direction of the induced electromotive force of the winding is consistent with that of the current.
4. The reference direction of the electromotive force in the secondary winding is consistent with that of the current.
5. The reference direction of the voltage in the secondary winding is consistent with that of the current.

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