Electrical Engineering MCQ 4

1. Dielectric strength in case of mica can be expected to be more than

(A) 500 kV/mm

(B) 1500 kV/mm

(C) 2500 kV/mm

(D) 3500 kV/mm.

2. All of the following dielectric materials are preferred for high frequency applications EXCEPT

(A) Polyethylene

(B) Butyl rubber

(C) Teflon

(D) Polystyrene.

3. Polar dielectrics are normally used for

(A) high frequencies

(B) microwaves

(C) dc and power frequencies

(D) none of the above.

4. Which of the following is a polar dielectric ?

(A) Teflon

(B) Quartz

(C) Nylon

(D) Polyethylene.

5. Which of the following is a non-polar dielectric ?

(A) Polystyrene

(B) Phenolic plastics

(C) Plasticized cellulose acetate

(D) Castor oil.

6. The impurity in liquid dielectric which has significant effect in reducing the breakdown strength, is

(A) dust

(B) dissolved gases

(C) moisture

(D) ionic impurities.

7. The relationship between the breakdown voltage V and gap d is normally given as

(A) d = kV2

(B) d=kV3

(C) V = kd

(D) v = kdn.

8. A good dielectric should have all the following properties EXCEPT

(A) high mechanical strength

(B) high resistance to thermal deterioration

(C) high dielectric loss

(D) freedom from gaseous inclusions.

9. The variety of paper used for insulation purpose is

(A) blotting paper

(B) rice paper

(C) craft paper

(D) mill-board.

10. Which variety of mica is hard and brittle ?

(A) Muscovite

(B) Phlogopite

(C) Fibiolite

(D) Lipidolite.

11. Corona effect can be identified by

(A) bushy sparks

(B) faint violet glow

(C) red light

(D) arcing between conductors and earth.

12. The phenomenon of corona is generally accompanied by

(A) a bang

(B) a hissing sound

(C) magnetic hum

(D) all of the above.

13. Van de Graaff generators are useful for

(A) Very high voltage and low current applications

(B) Very high voltage and high current applications

(C) Constant high voltage and current applications

(D) High voltage pulses only.

14. In Van de Graaff generators output voltage is controlled by

(A) controlling the corona source voltage

(B) controlling the belt speed

(C) controlling the lower spray point

(D) any of the above.

15. A Tesla coil is a

(A) cascaded transformer

(B) coreless transformer

(C) high frequency resonant transformer

(D) low impedance transformer.

1.A ----- 2.B ----- 3.C ----- 4.C ----- 5.A ----- 6.C ----- 7.D ----- 8.C -----9.C -----10.D -----11.B ----- 12.B -----13.A -----14.A ----- 15.C