Ques.1. Find H = ___________ A/m at the center of a circular coil of diameter 1 m and carrying a current of 2 A.
Ques.2. Hysteresis loss is ________ proportional to the area under the hysteresis curve. Also, it is ________ proportional to the number of cycles of magnetization per second:
- Directly, inversely
- Inversely, directly
- Directly, directly
- Inversely, inversely
Ques.3. Which of the following materials is used for the generation of ultrasonic waves by using magnetostriction effect?
- Paramagnetic material
- Ferromagnetic material
- Diamagnetic materials
- Both paramagnetic and diamagnetic material
Ques.4. If a circular conductor carries a current of ‘I’ ampere having radius ‘r’ meter, then the magnetizing force at the center of the coil is given by ;
- I/4r AT/m
- I/r AT/m
- I/2r AT/m
- I/2r AT/wb
Ques.5. What is the relationship between magnetic field strength and current density?
- ∇.H = J
- ∇.J = H
- ∇ × H = J
- ∇ × J = H
Ques.6. Two identical coils A and B of 1000 turns each lie in the parallel plane such that 80% of the flux produced by one coil links with the other. If a current of 5 A flowing in A produces a flux of 0.05 mWb, then the flux linking with coil B is:
- 0.4 mWb
- 0.04 mWb
- 4 mWb
- 0.004 mWb
Ques.7. The current flowing through a coil of 2 H inductance is decreasing at a rate of 4 A/s. What will be the induced EMF in the coil?
- 8 V
- – 8 V
- – 4 V
- 4 V
Ques.8. Magnetic flux will be _________ if the surface area vector of a surface is perpendicular to the magnetic field.
Ques.9. The force on the current-carrying conductor in a magnetic field depends upon:
(a) the flux density of the field
(b) The strength of the current
(c) The length of the conductor perpendicular to the magnetic field
(d) The directions of the field and the current
Ques.10. Calculate the flux density at a distance of 5 cm from a long straight circular conductor carrying a current of 250 A and placed in air.