The purpose of providing iron core in a step-up transformer is

The correct answer is: D. To provide all above features.

The iron core of a transformer provides a path for the magnetic flux to flow, which increases the magnitude of the mutual flux. This, in turn, increases the magnitude of the induced voltage in the secondary winding. The iron core also helps to reduce the magnetizing current, which makes the transformer more efficient.

Here is a more detailed explanation of each option:

• Option A: To provide coupling between primary and secondary. The iron core provides a path for the magnetic flux to flow, which couples the primary and secondary windings. This coupling is essential for the transformer to work.
• Option B: To increase the magnitude of mutual flux. The iron core increases the magnitude of the mutual flux by providing a low-reluctance path for the magnetic flux to flow. This, in turn, increases the magnitude of the induced voltage in the secondary winding.
• Option C: To decrease the magnitude of magnetizing current. The iron core helps to reduce the magnetizing current by providing a low-reluctance path for the magnetic flux to flow. This, in turn, makes the transformer more efficient.

Therefore, the correct answer is: D. To provide all above features.