Question

A basic one-loop dc generator is rotated at $90rev/s$. How many times each second does the dc output voltage peak (reach maximum)?

• A. $90$
• B. $180$
• C. $270$
• D. $360$

Answer 1

The correct option is B $180$

Instantaneous induced voltage is given by $E=NBAw\sin wt$
Now, instantaneous induced emf becomes maximum twice in one complete rotation at $wt={90}^o$ and ${270}^o$. Thus two voltage peaks are observed in one complete rotation.
Since the loop does $90$ revolution per second. So $180$ voltage peaks are observed per second.