3- The transformer is basically a voltage control device that is widely used in the distribution and transmission of alternating current. In a step...

3- The transformer is basically a voltage control device that is widely used in the distribution and transmission of alternating current. In a step-up transformer, the output voltage is increased; and in a step-down transformer, the output voltage is decreased. The step-up transformer will decrease the output current; while the step-down transformer will increase the output current to keep the input and output power of the system equal. Regarding the principles and operation of transformers, classify V for true statements and F for false statements:


( ) The efficiency of a transformer is about 50%.
( ) A transformer cannot increase or decrease the voltage of a DC source because Faraday's laws of electromagnetic induction are not valid.
( ) The high voltage winding has a larger cross-sectional area.