# ONLINE MCQ EE-ELECTROMAGNETIC INDUCTION 3

Q21. The self inductance’s of two coils are 8
mH and 18 mH If the co-efficient s of
coupling is 0.5, the mutual inductance
of the coils is
A.  4 mH
B.  5 mH
C.  6 mH
D.  12 mH
 \$(document).ready(function(){ \$(‘#loaddata2120’).click(function(){ qid2120=\$(‘#qid2120’).val(); section2120=\$(‘#section2120’).val(); type2120=\$(‘#type2120’).val(); subtype2120=\$(‘#subtype2120’).val(); \$.post(‘../../fav’,{ qid:qid2120, section: section2120, type: type2120, subtype: subtype2120 },function(ajaxresult){ \$(‘#getrequest2120’).html(ajaxresult); qid2120=\$(‘#qid2120’).val(”); section2120=\$(‘#section2120’).val(”); type2120=\$(‘#type2120’).val(”); subtype2120=\$(‘#subtype2120’).val(”); }); }); }); Explanation:- Answer : C

Q22. A 500 turns solenoid develops an
average induced voltage of 60 V. Over
what time interval must a flux change
of 0.06 Wb occur to produce such a
voltage?
A.  0.01 s
B.  0.1 s
C.  0.5 s
D.  5 s
 \$(document).ready(function(){ \$(‘#loaddata2121’).click(function(){ qid2121=\$(‘#qid2121’).val(); section2121=\$(‘#section2121’).val(); type2121=\$(‘#type2121’).val(); subtype2121=\$(‘#subtype2121’).val(); \$.post(‘../../fav’,{ qid:qid2121, section: section2121, type: type2121, subtype: subtype2121 },function(ajaxresult){ \$(‘#getrequest2121’).html(ajaxresult); qid2121=\$(‘#qid2121’).val(”); section2121=\$(‘#section2121’).val(”); type2121=\$(‘#type2121’).val(”); subtype2121=\$(‘#subtype2121’).val(”); }); }); }); Explanation:- Answer : C

Q23. A coil is wound on iron core which carries
current I. The self induced voltage
in the coil is not affected by
A.  variation in coil current
B.  variation in voltage to the coil
C.  change of number of turns of coil
D.  the resistance of magnetic path
 \$(document).ready(function(){ \$(‘#loaddata2122’).click(function(){ qid2122=\$(‘#qid2122’).val(); section2122=\$(‘#section2122’).val(); type2122=\$(‘#type2122’).val(); subtype2122=\$(‘#subtype2122’).val(); \$.post(‘../../fav’,{ qid:qid2122, section: section2122, type: type2122, subtype: subtype2122 },function(ajaxresult){ \$(‘#getrequest2122’).html(ajaxresult); qid2122=\$(‘#qid2122’).val(”); section2122=\$(‘#section2122’).val(”); type2122=\$(‘#type2122’).val(”); subtype2122=\$(‘#subtype2122’).val(”); }); }); }); Explanation:- Answer : B

Q24. An open coil has
A.  zero resistance and inductance
B.  infinite resistance and zero inductance
C.  infinite resistance and normal inductance
D.  zero resistance and high inductance
 \$(document).ready(function(){ \$(‘#loaddata2123’).click(function(){ qid2123=\$(‘#qid2123’).val(); section2123=\$(‘#section2123’).val(); type2123=\$(‘#type2123’).val(); subtype2123=\$(‘#subtype2123’).val(); \$.post(‘../../fav’,{ qid:qid2123, section: section2123, type: type2123, subtype: subtype2123 },function(ajaxresult){ \$(‘#getrequest2123’).html(ajaxresult); qid2123=\$(‘#qid2123’).val(”); section2123=\$(‘#section2123’).val(”); type2123=\$(‘#type2123’).val(”); subtype2123=\$(‘#subtype2123’).val(”); }); }); }); Explanation:- Answer : B

Q25. The law that the induced e.m.f. and
current always oppose the cause
producing them is due to
B.  Lenz
C.  Newton
D.  Coulomb
 \$(document).ready(function(){ \$(‘#loaddata2124’).click(function(){ qid2124=\$(‘#qid2124’).val(); section2124=\$(‘#section2124’).val(); type2124=\$(‘#type2124’).val(); subtype2124=\$(‘#subtype2124’).val(); \$.post(‘../../fav’,{ qid:qid2124, section: section2124, type: type2124, subtype: subtype2124 },function(ajaxresult){ \$(‘#getrequest2124’).html(ajaxresult); qid2124=\$(‘#qid2124’).val(”); section2124=\$(‘#section2124’).val(”); type2124=\$(‘#type2124’).val(”); subtype2124=\$(‘#subtype2124’).val(”); }); }); }); Explanation:- Answer : B

Q26. Two coils have inductances of 8 mH and
18 mH and a co-efficient of coupling of
0.5. If the two coils are connected in
series aiding, the total inductance will
be
A.  32 mH
B.  27 mH
C.  40 mH
D.  48 mH
 \$(document).ready(function(){ \$(‘#loaddata2125’).click(function(){ qid2125=\$(‘#qid2125’).val(); section2125=\$(‘#section2125’).val(); type2125=\$(‘#type2125’).val(); subtype2125=\$(‘#subtype2125’).val(); \$.post(‘../../fav’,{ qid:qid2125, section: section2125, type: type2125, subtype: subtype2125 },function(ajaxresult){ \$(‘#getrequest2125’).html(ajaxresult); qid2125=\$(‘#qid2125’).val(”); section2125=\$(‘#section2125’).val(”); type2125=\$(‘#type2125’).val(”); subtype2125=\$(‘#subtype2125’).val(”); }); }); }); Explanation:- Answer : B

Q27. Which of the following inductor will
have the least eddy current losses?
A.  Air core
B.  Laminated iron core
C.  Iron core
D.  Powdered iron core
 \$(document).ready(function(){ \$(‘#loaddata2126’).click(function(){ qid2126=\$(‘#qid2126’).val(); section2126=\$(‘#section2126’).val(); type2126=\$(‘#type2126’).val(); subtype2126=\$(‘#subtype2126’).val(); \$.post(‘../../fav’,{ qid:qid2126, section: section2126, type: type2126, subtype: subtype2126 },function(ajaxresult){ \$(‘#getrequest2126’).html(ajaxresult); qid2126=\$(‘#qid2126’).val(”); section2126=\$(‘#section2126’).val(”); type2126=\$(‘#type2126’).val(”); subtype2126=\$(‘#subtype2126’).val(”); }); }); }); Explanation:- Answer : A

Q28. Which of the following statements is correct ?
A.  The inductance of the coil carrying
a constant D.C. current will change
the current into pulses
B.  The inductance of the coil carrying
a constant D.C. current will increase
the current
C.  The inductance of the coil carrying
a constant D.C. current will not affect
the current
D.  The inductance of the coil carrying
a constant D.C. current will
decrease the current
 \$(document).ready(function(){ \$(‘#loaddata2127’).click(function(){ qid2127=\$(‘#qid2127’).val(); section2127=\$(‘#section2127’).val(); type2127=\$(‘#type2127’).val(); subtype2127=\$(‘#subtype2127’).val(); \$.post(‘../../fav’,{ qid:qid2127, section: section2127, type: type2127, subtype: subtype2127 },function(ajaxresult){ \$(‘#getrequest2127’).html(ajaxresult); qid2127=\$(‘#qid2127’).val(”); section2127=\$(‘#section2127’).val(”); type2127=\$(‘#type2127’).val(”); subtype2127=\$(‘#subtype2127’).val(”); }); }); }); Explanation:- Answer : C

Q29. Both the number of turns and the core
length of an inductive coil are doubled.
Its self-inductance will be
A.  unaffected
B.  doubled
C.  halved