Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It only takes a minute to sign up.
Sign up to join this community
If a resistor is connected on the secondary let's say 2 Ohms, this would have an overall effect on the primary & secondary circuit of a Transformer. It is obvious that the resistor would affect the Secondary circuit as they are 'physically' connected.
But the resistor isn't physically connected to the Primary, so how does the Primary know there is a resistor in the Secondary and the current (in the Primary) flows/acts as if the resistor from the secondary has been connected to the Primary?
Just like how the induction coil in an induction motor feels the resistance of the load on the rotor. A magnetic field moving relative to a charged particle or vise versa experiences a force on it equal and opposite to the force on the particle, then it all comes down to which will be the static or the dynamic. That's why electron flow in the coil of an induction motor makes the induced magnetic rotor spin just because it's the freely moving part of the interaction. The primary coil of a transformer creates the alternating magnetic field and the effect is forces on the electrons in the secondary coil or any other charged particle around. If somehow the forces exerted on the secondary coil electrons are resisted/opposed by something, the cause of the force also has to feel the same resistance too. Think of it as you having a power to transmit your efforts across space, and you've got a large boulder to push, now if you try pushing the rock with your power, you feel the resistance against motion due to inertia or maybe gravity if inclined because even though it's across three dimensional space, you are still linked to the boulder like you are touching it. It's just down to the third law of motion in a field effect.
