I want to ask a question about transformers. Primary and secondary parts are isolated electrically and there is only a magnetic coupling. If there is a short circuit in the secondary part, is our primary current affected by this problem or not? Because there is not any electrical connection.
It's not like a solar panel being shorted i.e. the sun stays the same brightness despite the short. A transformer converts electrical energy to magnetic energy and then back to electrical energy. It does it with pretty good efficiency (90%+ on most transformers). If you short the secondary, the primary takes a lot of current. It's the same with an electric motor - if you lock the armature, you take a lot of current/power/energy.
In a transformer, power is equal on both sides.
When short circuiting the secondary side, with V=IR, the current increases and thus with P=VI, the power increases on the secondary side.
This makes the power increase on the primary side as well. Assuming a constant voltage on the primary side, with P=VI, the current will increase as well, up to the limits of the components.