Elements of Electrical Engineering - Dec 2015
First Year Engineering (Semester 1)
TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
Objective Question ? select only one option out of four (MCQ)
1(a)1 Which of the following material has nearly zero temperature co-efficient of
[d] Manganin(1 marks) 1(a)2 The unit of absolute permittivity of a medium is
[d] joule/coulomb(1 marks) 1(a)3 The unit of resistivity is
[a] Ohm / m
[c] mho/m [d] mho-m(1 marks) 1(a)4 Time constant of an R-C ckt. may be defined as
[a] time during which capacitor voltage rises to 0.632 of its initial value
[b] time during which charging current falls to 0.37 of its initial max. Value
[c] time during which capacitor voltage falls to 0.632 of its final steady value
[d] time during which charging current rises to 0.37 of its initial max. value(1 marks) 1(a)5 The unit of reluctance is
[a] AT / Wb
[b] Wb / AT
[d] either [b] or [c](1 marks) 1(a)6 Wh efficiency of lead-acid cell is ______ Ah efficiency.
[a] greater than
[b] smaller than
[c] equal to
[d] none of this(1 marks) 1(a)7 The value of form factor is
[d] 14.14(1 marks) 1(b)1 The value of power factor is zero for
[a] purely inductive ckt.
[b] purely resistive ckt.
[c] purely capacitive ckt.
[d] either [a] or [c](1 marks) 1(b)2 For a series resonance condition of AC circuit impedance is
[d] infinity(1 marks) 1(b)3 The filament used in incandescent lamp is made of
[d] tungsten(1 marks) 1(b)4 The value of crest factor is
[d] 14.14(1 marks) 1(b)5 For a parallel resonance condition of a AC circuit current is
[d] infinity(1 marks) 1(b)6 For unity power factor load of 3-phase ckt.,if we measure the power by 2- wattmeter method then readings of wattmeters are
[a] one wattmeter shows zero reading
[b] equal & +ve sign
[c] equal & opposite sign
[d] both shows zero reading The power factor of R-C series Ac ckt. is(1 marks) 1(b)7 The power factor of R-C series Ac ckt. Is
[d] zero(1 marks)