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Friday, 4 September 2015

Magnetic Effect of Electric Current - Multiple Choice Questions, Blanks & True False

Magnetic Effect of Electric Current - Multiple Choice Questions, Blanks & True False Points : magnetic effect of electric current, multiple choice questions and answer,magnetic effect of electric current - fill in the blanks,magnetic effect of electric current - true or false, magnetic effect of electric current mcqs, objective type questions principles of electrical engineering Multiple Choice Questions 1. The ratio of mmf and flux of magnetic circuit is called
(a) Reluctance
(b) Capacitance
(c) Inductance

2. Second name of B-H curve is
(a) Magnetic Hysteresis
(b) Hysteresis loop
(c) Hysteresis curve

3. Permanent magnets are commonly made of
(a) Cast iron
(b) Alnico Alloy
(c) Aluminium

4. The unit of magnetic flux density is
(a) Tesla
(b) Lumens
(c) Weber

5. The link between magnetizing force and magnetic flux density is
(a) B=H/μ
(b) B=μH
(c) B=μH

6. The value of μ for air is
(a) 1
(b) 2
(c) 3

7. If the number of turns and length of core increased in double, then self inductance.
(a) Half
(b) Double
(c) One fourth

8. The property, of material which oppose the produced magnetic flux is called.
(a) Permeance
(b) Inductance
(c) Reluctance

9. The inverse of permeance is
(a) Reluctance
(b) Inductance
(c) Impedance

10. The inverse of permeability is
(a) Inductivity
(b) Reluctivity
(c) Conductivity
Fill in the blanks 1. The force of attraction is found in the opposite poles.
2. The second name of Fleming’s left hand rule is also called motor rule.
3. Weber is the unit of magnetic flux.
4. Air is non magnetic.
5. The unit of inductance is henry.
6. Magnetic field always perpendicular on the conductor.
7. The inverse of reluctance is pemeance.
8. The unit of mmf is ampere turns.
9. Flux per unit area is called flux density.
True and False 1. The unit of magnetic flux is weber. T
2. An inductor for d.c. voltage act as open circuit. F
3. Relative permeability in vacuum is 1/4π. F
4. Gulburt is the unit of mmf. T
5. The lifting power of electromagnet depends on inductance. T
6. Direction of produced emf can be determined by Kirchhoff’s law. F
7. In B-H curve, B on y-axis and H on x-axis. T
8. When a conductor cuts the magnetic field, then emf is produced is called Joule’s law. F
9. Every line of magnetic flux move a closed loop. T
10. The flux density is equal to Ф / H. F

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