## electrical

### Magnetism and Electromagnetism MCQ Page - 2

1.
 Susceptibility is positive for A Non-magnetic substance B Diamagnetic substance C Ferromagnetic substance D None of the above Answer : C Explanation :
2.
 Two long parallel conductors carry 100 A. if the conductors are separated by 20 mm, the force per meter of length of each conductor will be A 100 N B 10 N C 1 N D 0.1 N Answer : D Explanation :
3.
 The tubes of force within the magnetic materials are known as A Electric flux B Lines of force C Tubes of induction D None of the above Answer : B Explanation :
4.
 The unit of flux is same as that of A Reluctance B Resistance C Permeance D Pole strength Answer : D Explanation :
5.
 Unit of quantity of electricity is A Ampere-hour B Watt C Joule D Coulomb Answer : D Explanation :
6.
 The Biot-savart’s law is a general modification of A Kirchhoff’s law B Lenz’s law C Ampere’s law D Faraday’s law Answer : C Explanation :
7.
 The most effective and quickest way of making magnet from soft iron is by A Placing it inside a coil carrying current B Induction C The use of permanent magnet D Rubbing with another magnet Answer : A Explanation :
8.
 The commonly used material for shielding or screening magnetism is A Copper B aluminium C Soft iron D Brass Answer : C Explanation :
9.
 If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity A Less than that of disc but in opposite direction B Equal to that of disc and in the same direction C Equal to that of disc and in opposite direction D Less than that of disc and in the same direction Answer : D Explanation :
10.
 A permanent magnet A Attracts some substances and repels other B Attracts all paramagnetic substance and repels other C Attracts only ferromagnetic substances D Attracts ferromagnetic substances and repels other Answer : A Explanation :
11.
 The retentivity (a property) of material is useful for construction of A permanent magnet B Transformer C Non-magnetic substance D Electromagnet Answer : A Explanation :
12.
 The relative permeability of ………… a material is not constant A Diamagnetic B Paramagnetic C Ferromagnetic D Insulating Answer : C Explanation :
13.
 The ………. Materials are a bit inferior conductor of magnetic flux than air. A Ferromagnetic B Paramagnetic C Diamagnetic D Dielectric Answer : C Explanation :
14.
 Hysteresis loop in case of magnetically hard materials is more …….. in shape as compared to magnetically soft materials. A Circular B Triangular C Rectangular D None of the above Answer : C Explanation :
15.
 A rectangular magnet of magnetic moment M is cut into two pieces of same length, the magnetic moment of each piece will be A M B M/2 C 2M D M/4 Answer : B Explanation :
16.
 A keeper is used to A Change the direction of magnetic lines B Amplify flux C Restore lost flux D Provide a close path for flux Answer : D Explanation :
17.
 Magnetic moment is a A Change in direction of magnetic lines B Amplify flux C Restore lost flux D Provide a close path for flux Answer : D Explanation :
18.
 The change of cross-sectional area of conductor in magnetic field will affect A Reluctance of conductor B Resistance of conductor C (a) and (b) both in the same way D None of the above Answer : C Explanation :
19.
 The uniform magnetic field is A The field of a set of parallel conductors B The field of a single conductor C The field in which all lines of magnetic flux are parallel and equidistant D None of the above Answer : C Explanation :
20.
 The magneto-motive force is A The voltage across the two ends of exciting coil B The flow of an electric current C The sum of all currents embraced by one line of magnetic field D The passage of magnetic field through an exciting coil Answer : C Explanation :
21.
 What will be the current passing through the ring-shaped air cored coil when numbers of turns is 800 and amperes turns are 3200? A 2 B 4 C 6 D 8 Answer : B Explanation :
22.
 What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m? A 2 AT B 4 AT C 6 AT D 10 AT Answer : B Explanation :
23.
 A certain amount of current flows through a ring-shaped coil with fixed numbers of turns. How the magnetic induction B does varies inside the coil if an iron core is threaded into coil without dimensionless change of coil? A Decrease B Increases C Remain same D First increases and then decreases depending on the depth of iron insertion Answer : B Explanation :
24.
 The magnetic reluctance of materials A Decrease with increasing cross-sectional area of material B Increases with increasing cross-sectional area of material C Does not vary with increasing cross-sectional area of material D Any of the above Answer : A Explanation :
25.
 The initial permeability of an iron rod is A The highest permeability of the iron rod B The lowest permeability of the iron rod C The permeability at the end of the iron rod D The permeability almost in non-magnetised state Answer : D Explanation :
26.
 Which path of the magnetic path requires largest m.m.f? A Air gap B Coil C Inductance D Core Answer : A Explanation :
27.
 How does the magnetic compass needle behave in a magnetic field? A It assures a position right angle to magnetic field B It starts rotating C It assures a position right angle to magnetic field D None of the above Answer : C Explanation :
28.
 In a simple magnetic field the strength of magnetic flux A Is constant and has same value in energy part of the magnetic field B Increases continuously from initial value to final value C Decreases continuously from initial value to final value D First increases and then decreases till it becomes zero Answer : A Explanation :
29.
 The stray line of magnetic flux is defined as A A line vertical to the flux line B The mean length of a ring-shaped coil C A line of magnetic flux in anon-uniform field D A line of magnetic flux which does not follow the designed path Answer : D Explanation :
30.
 The bar magnet has A The dipole moment B Monopole moment C (a) and (b) both D None of the above Answer : A Explanation :
31.
 Which of the following materials are diamagnetic? A Silver B Copper C Silver and copper D Iron Answer : C Explanation :
32.
 Which of the following type of materials are not very important for engineering applications? A Ferromagnetic B Paramagnetic C Diamagnetic D None of the above Answer : C Explanation :
33.
 The susceptibility of paramagnetic materials generally lies between A 10-3and 10-5 B 10-3and 10-7 C 10-4and 10-8 D 10-2and 10-5 Answer : A Explanation :
34.
 For which of the following material of saturation value is highest? A Ferromagnetic materials B Paramagnetic materials C Diamagnetic materials D Ferrites Answer : D Explanation :
35.
 The magnetic materials exhibit the property of magnetisation because of A Orbital motion of electrons B Spin of electrons C Spin of nucleus D All of the above Answer : D Explanation :
36.
 For which of the following materials the net magnetic moment should be zero? A Diamagnetic materials B Ferromagnetic material C Antiferromagnetic materials D Antiferromagnetic materials Answer : C Explanation :
37.
 The attraction capacity of electromagnet will increase if the A Core length increase B Core area increases C Flux density decreases D Flux density increases Answer : D Explanation :
38.
 Which of the following statement is correct? A The conductivity of ferrites is better than ferromagnetic materials B The conductivity of ferromagnetic material is better than ferrites C The conductivity of ferrites is very high D The conductivity of ferrites is same as that of ferromagnetic materials Answer : A Explanation :
39.
 The magnetisation and applied field in ferromagnetic materials are related A Sinusoidally B Linearly C Non-linearly D Parabolically Answer : C Explanation :
40.
 In which of the materials the spin moments associated with two sets of atoms are aligned antiparallel to each other? A Ferromagnetic material B Ferrites C Ferromagnetic materials D Anti-ferromagnetic materials Answer : D Explanation :
41.
 Temporary magnets are used in A Loud-speaker B Generators C Motors D All of the above Answer : D Explanation :
42.
 Strength of electromagnet can be increased by A Increasing the cross-sectional area B Increasing the number of turns C Increasing the current supply D All above methods Answer : D Explanation :
43.
 Core of electromagnet should have A Low coercivity B High susceptibility C Both of the above D None of the above Answer : C Explanation :
44.
 Magnetism of a magnet can be destroyed by A Heating B Hammering C By inductive action of another magnet D By all of the above Answer : D Explanation :