UNIT-II
AC CIRCUITS AND TRANSFORMERS
1. What is meant by average value?
The average value of an alternating current is defined as the D.C. current which transfers across
any circuit the same charge as is transferred by that alternating current during the same time.
Average value = Area under the curve for one complete cycle
Base (time period)
2. Define RMS value.
The steady current which when flowing through a given resistor for a given time produces the
same amount of heat as produced by the alternating current when flowing through the same resistor for
the same time is called R.M.S or effective value of the alternating current.
RMS value= area the square for one cycle
Period
3. Define form factor.
It is defined as the ratio of RMS value of current (voltage) to the average value of current
(voltage).
Form factor = RMS value
Average value
4. Define peak factor.
It is defined as the ratio of maximum value of current (voltage) to the RMS value of current (voltage).
Peak factor = Maximum value
RMS value
5. Distinguish between power and energy.
Sl.No Power Energy
1. The rate at which work is done is called The capacity to do work or the total work done is
electric power. called energy.
2. Power (P) = VI Energy = VIt
Where V—Voltage Where V—Voltage
I – Current I --- Current
t --- Time
3. Unit : Watts Unit : Watt-Hour
AC CIRCUITS AND TRANSFORMERS
1. What is meant by average value?
The average value of an alternating current is defined as the D.C. current which transfers across
any circuit the same charge as is transferred by that alternating current during the same time.
Average value = Area under the curve for one complete cycle
Base (time period)
2. Define RMS value.
The steady current which when flowing through a given resistor for a given time produces the
same amount of heat as produced by the alternating current when flowing through the same resistor for
the same time is called R.M.S or effective value of the alternating current.
RMS value= area the square for one cycle
Period
3. Define form factor.
It is defined as the ratio of RMS value of current (voltage) to the average value of current
(voltage).
Form factor = RMS value
Average value
4. Define peak factor.
It is defined as the ratio of maximum value of current (voltage) to the RMS value of current (voltage).
Peak factor = Maximum value
RMS value
5. Distinguish between power and energy.
Sl.No Power Energy
1. The rate at which work is done is called The capacity to do work or the total work done is
electric power. called energy.
2. Power (P) = VI Energy = VIt
Where V—Voltage Where V—Voltage
I – Current I --- Current
t --- Time
3. Unit : Watts Unit : Watt-Hour
