An equipotential surface is a surface in an electric field such that all points on it are at the

A)Same potential 
B)Different potential 
C)Different frequency 
D)Same frequency

In a.c. voltage regulator with R-L load

A)the current leads the voltage
B)current will lead or lag the voltage depending on the L/R ratio 
C)the voltage lags the current
D)the voltage leads the current

Load voltage in a d.c. chopper circuit is given by / d.c.

A)d.c. supply voltage /duty cycle 
B)Duty cycle X d.c. supply voltage 
C)Duty cycle/ d.c. supply voltage
D)1/(duty cycle X d.c. supply voltage)