Question

The primary and secondary windings of a
transformer are
coupled to each other.
A. electrically
B. magnetically
C. electrically and magnetically
D. none of the above.

Answer 1

There is no physical coupling in transformers . Primary is coupled magnetically with secondry winding . Let us have a look at the picture below to understand the concept better


Leave all the other parameters of the equivalent circuit of transformers aside . Just have a look at the symbol There is a gap between them isn’t it ?

Transformer works on the principle of mutual inductance . i.e When there is a changing magnetic flux the voltage will be induced ( law of electro magnetic induction ) . AC (Alternating current) provides that changing magnetic flux and accordingly voltage is induced in the secondary winding .

Note :- This is the main reason there is nothing like DC transformers . DC (Direct current) does not produce changing flux so it cant be magnetically coupled .

Had there been no transformers there wohld have been no power transmission of low voltages from one place to other .

Answer 2

Option b magnetically describes the primary and secondary windings of a transformer.

Explanation:

Magnetically

• The coefficient of coupling between the primary and secondary coils in an ideal transformer should equal 1.
• They should be fully magnetically linked, in other words.
• The electromagnetic induction between the coils will be more efficient if they are magnetically linked well.

Electrically

• The primary winding and secondary winding are the two windings that make up a standard transformer.
• Magnetically linked and electrically separated, these two windings.
• Due to a common mutual flux, the main and secondary windings of a two-winding transformer have induced emf and are thus in phase. Then the statement  is wrong

Electrically and magnetically

• The primary winding and secondary winding are the two windings that make up a standard transformer.
• Magnetically linked and electrically separated, these two windings.
• Due to a common mutual flux, the main and secondary windings of a two-winding transformer have induced emf and are thus in phase.
• Then the statement  is wrong

none of the above.

• The coefficient of coupling between the primary and secondary coils in an ideal transformer should equal 1.
• They should be fully magnetically linked, in wrong other words.
• The electromagnetic induction between the coils will be more efficient if they are magnetically linked well.
• Then the statement is wrong