Why is secondary voltage in transformer changes with increase in load?

Loading the secondary winding with a simple load impedance causes a secondary current to flow, at any power factor, through the internal winding of the transformer. Thus voltage drops due to the windings internal resistance and its leakage reactance causes the output terminal voltage to change.

Why does secondary terminal voltage decrease when a load on a transformer increases?

This resistance is combination of winding resistance and reflected reactance of the primary. As load increases, load current increases. This will increase voltage drop across Zth i.e. equivalent internal resistance of the transformer. Hence load or terminal voltage of transformer will decrease.

Why number of turns in secondary coil is the deciding factor of increase or decrease in voltage current?

Working of step-up transformer is based on the principle of mutual inductance and it converts the alternating low voltage to alternating high voltage. The number of turns in the secondary coil is greater than the number of turns in the primary coil. The emf is induced in the coil as per Faraday’s law.

How does secondary voltage increase?

So if you want a 12V secondary you wind 12 turns; 24V requires 24 turns, etc. If you want the transformer to increase voltage, you have to add more turns. The one volt per turn transformer would make 200 volts with 200 turns; 240 volts with 240 turns etc.

Which is true about a transformer that has fewer secondary turns than primary turns?

Question: Which is true about a transformer that has fewer secondary turns than primary turns? The secondary current is less than the primary current, and the equivalent resistance is greater than the actual resistance.

Why does the voltage increase in a transformer?

As the magnetic field expands, it induces current in the second coil. The voltage across the second coil increases as long as the magnetic field expands. When the magnetic field begins to collapse, the voltage across the second coil begins to decrease.