Which of the following statements are correct about transformers?

A. Transformers can not be used to step up DC.
B. The frequency of output across the secondary is always equal to the frequency of input across the primary.
C. The output power of a transformer may be increased to a value which is more than the input power.
D. Transformation ratio is equal to turns ratio.
E. In a step up transformer, secondary current is less than primary current.

Choose the correct answer from the options given below:

A, B, D, E

Following statements are correct about transformers

A. Transformers can not be used to step up DC.
B. The frequency of output across the secondary is always equal to the frequency of input across the primary.
D. Transformation ratio is equal to turns ratio.
E. In a step up transformer, secondary current is less than primary current.

Only One statement is incorrect

C. The output power of a transformer may be increased to a value which is more than the input power.  As this violates principle of conservation of energy