MCQs of Magnetic fields and magnetic circuits (Electrical Machine - I - 3140913)

Electrical Machine - I (3140913) MCQs

MCQs of Magnetic fields and magnetic circuits

Showing 11 to 20 out of 40 Questions

11.

A substance whose permeability is more than the permeability of free space is?

(a)	Diamagnetic
(b)	Paramagnetic
(c)	Ferromagnetic
(d)	Both paramagnetic and ferromagnetic

12.

The unit for permeability of free space is?

(a)	Henry
(b)	Henry-m
(c)	Henry/m
(d)	Henry/m²

13.

Calculate the magnetic flux density (T) if the magnetic field strength is 2A/m.

(a)	$4 π 10^{- 7}$
(b)	$8 π 10^{- 7}$
(c)	$12 π 10^{- 7}$
(d)	$12.5 π 10^{- 7}$

14.

What is the unit for relative permeability?

(a)	H-m
(b)	H/m
(c)	H²/m
(d)	No unit

15.

Which of the following expressions is correct with respect to relative permeability?

(a)	$B = μ_{r} μ_{0} H$
(b)	$B = \frac{μ_{r} μ_{0}}{H}$
(c)	$B = μ_{r} μ_{0} H^{2}$
(d)	$B = \frac{μ_{r} μ_{0}}{H^{2}}$

16.

As the temperature increases up to the Curie temperature, the relative susceptibility of ferromagnetic materials?

(a)	Increases
(b)	Decreases
(c)	Remains constant
(d)	Becomes zero

17.

(i) When the length of the material increases, what happens to reluctance? (ii) When the area of cross-section of the material increases, what happens to reluctance?

(a)	(i) Increase (ii) Decrease
(b)	(i) Increase (ii) Increase
(c)	(i) Decrease (ii) Increase
(d)	(i) Constant (ii) Constant

18.

Unit of reluctance is?

(a)	A W_b
(b)	A²/W_b
(c)	W_b/A
(d)	A/W_b

19.

Calculate the reluctance (A/Wb) when the magnetomotive force is 10 A-turns and the flux is 5Wb.

(a)	0.5
(b)	1
(c)	2
(d)	4

20.

The electrical equivalent of reluctance is?

(a)	Resistance
(b)	Inductance
(c)	Capacitance
(d)	Conductance

Showing 11 to 20 out of 40 Questions