When an alternating current passes through an ohmic resistance the electrical power converted into heat is__________?

Related Mcqs:

1. The r.m.s. value of alternating current is given by steady (D.C.) current which when flowing through a given circuit for a given time produces__________?

   A. the more heat than produced by A.C. when flowing through the same circuit
   B. the same heat as produced by A.C. when flowing through the same circuit
   C. the less heat than produced by A.C. flowing through the same circuit
   D. none of the above

2. The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes_______ohms?

   A. 2.5
   B. 5
   C. 10
   D. 15

3. In the case of an unsymmetrical alternating current the average value must always be taken over__________?

   A. unsymmetrical part of the wave form
   B. the quarter cycle
   C. the half cycle
   D. the whole cycle

4. The frequency of an alternating current is____________?

   A. the speed with which the alternator runs
   B. the number of cycles generated in one minute
   C. the number of waves passing through a point in one second
   D. the number of electrons passing through a point in one second

5. The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is__________?

   A. 12 kW
   B. 22 kW
   C. 32 kW
   D. 64 kW

6. The power consumed in a circuit element will be least when the phase difference between the current and voltage is__________?

   A. 180″
   B. 90°
   C. 60°
   D. 0°

7. In each of the three coils of a three phase generator, an alternating voltage having an r.m.s. value of 220 V is induced. Which of the following values is indicated by the voltmeters ______?

   A. 220 V
   B. 220V3V
   C. 220/V3 V
   D. none of the above

8. What will be the phase angle between two alternating waves of equal frequency, when one wave attains maximum value the other is at zero value________ ?

   A. 0°
   B. 45°
   C. 90°
   D. 180°

9. Power factor of an electrical circuit is equal to____________?

   A. R/Z
   B. cosine of phase angle difference be-tween current and voltage
   C. kW/kVA
   D. ratio of useful current to total cur¬rent Iw/I
   E. all of these

10. The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of____________?

    A. iron loss in core
    B. skin effect
    C. increase in temperature
    D. capacitive effect between adjacent coil turns