Jan2018 ELECTRICIAN / ELECTROPLATOR / LIFT MECHANIC / LIFT & ESCALATOR MECHANIC / WIREMAN THEORY SEMESTER - 1

Jan2018 ELECTRICIAN / ELECTROPLATOR / LIFT MECHANIC / LIFT & ESCALATOR
MECHANIC / WIREMAN
THEORY SEMESTER - 1

Two wires A and B of the same material and length L and 2L have radius R and 2R respectively. The ratio of their specific resistance will be

Ideal voltage sources have
a) Zero internal resistance
b) Infinite internal resistance
c) Low value of current
d) Large value of emf

KirchhofPs laws are valid for
a) Linear circuit only
b) Passive time invariant circuits
c) Nonlinear circuits only
d) Both linear and nonlinear circuits

The unit of impedance is —
a) Ohms
b) Siemens
c) Mho
d) Henry

The value of peak factor of a sinusoidal waveform is
a) Zero
c) 1.11
d) 1.41

The algebraic sum of incoming current is equal to the sum of outgoing current is the statement of —
a) Kirchoffs current law
b) Kirchoffs voltage law
c) Ohm's law
d) .Joule's law

A 12 V battery under fully charged condition has open circuit voltage of—
a) 12 V
b) < 12 v

A 100 W, 220 volt lamps takes a current of 12 v  12 v
a) 5/1 1 A
b) 2.2 A
c) 0.22 A
d) 5/22 A

In a pure inductive A.C. circuit —
a) Voltage leads the current vector by 900
c) Current leads the voltage vector by 900  
b) Voltage legs the current vector by 90 0
d) Current is in phase with the voltage vector

The r.m.s. value of sinusoidal alternating current is given by the relation
a) 1m/2
b) 0.637 1m
C) 21m/7t

Primary battery is such a battery —
a) Which can be recharged
b) Which cannot be reconditioned by replacing chemical
c) Which cannot be reused
d) Which cannot be recharged

Internal resistance of a battery cell increases with
a) Increases in concentration of electrolyte
b) Increase in distance between two electrodes
c) Increases in area of the plates inside the electrolyte
d) Increase in size of the electrodes

If cells are connected in series, then will increase.
a) Current
b) Voltage
c) Power
d) Energy

If Z is the electro — Chemical equivalent of a substance of the electrolyte. E is the   chemical equivalent of the same substance, then the relation between Z & E will be —

Negative electrode or anode of simple voltaic cell is made of
a) Copper
b) Zinc
c) Lead
d) Carbon

E.C.E stands for
a)  chemical equivalent
b) Electrolysis cathode equivalent
c) Electro chemical equivalent
d) None of these
a) PIC)
b) P
C) - cm / 0 C

Permittivity of free space is equal to   c) PC) - cm

Resistivity of metals is expressed in terms of
a) x 10 P F/m
b) 8.84 x F / m
C) 8.84 X Il F/m
d) 8.84 x

Which resistor will be physically larger in size?
a) 100 Q, 10 W
b) 10 Q, 50 W
d) I ICQ, 1 W

Two resistor are said to be connected in parallel when
a) Same current passes in turn through both
b) Both carry the same value of current
c) Voltage across each resistance are same
d) Voltage across each resistance are not same

The electrical resistance of human body is around
a) 5 ohms
b) 25 ohms
c) 250 ohms
d) 1000 ohms

A 3 Q resistor having 2A current will dissipate the power of
d) 12 W

Three element having conductance G), G2 and G3 are connected in parallel. Their combined conductance will be
a) (Gl + Ci2 + Cig)" I
c) l/G! + l/G2 + l/G3+ 1/Ggy l

Which of the following materials has highest electrical conductivity?
a) Steel
b) Aluminium
c) Copper
d) Silver

If the phas€ angle between voltage and éurrent of a 1 -d) AC current is 600 , then power factor is the circuit is
a) 0.2
b) 0.5
c) 0.707
d) 1.0

The current in the resistor R shown in Figure will be
a) 0.2 A
b) 0.4 A
c) 0.6 A
d) 0.8 A

Which of the following has positive temperature coefficient?
a) Germanium
b) Gold c) Paper

Which law(s) find application in electrolysis? d) Rubber
a) Ohms' law
b) Gauss's law
c) Faradays' law d
d Coulomb's law

Silver coating is provided for
a) Protective purpose
b) Decorative purpose
c) Bearing surface
d) All of these

The permanent magnets are made from which of following materials?
a) Soft iron
b) Ferromagnetic
c) Paramagnetic
d) Diamagnetic

The Biot-savart's law is a general modification of—
a) Kirchhoffs law
b) Lenz's law
c) Ampere's law
d) Faradays' law
I Maxwell is the same as —
a) 10-8 weber
b) 10 8 weber
c) 104 weber
d) 1 weber

The direction of induced emf can be found by
a) Laplace's law
b) Kirchhoff's voltage law
c) Lenz's law

A closed switch has a resistance, of -
d) Fleming's right hand rule
a) Zero
b) About 50 ohms
c) About 500 ohms
d) Infinite

The energy stored in an inductor of indåctor L Henry is represented as
a) i2 L
b) iL2
C) (1/2)L12

The forbidden energy gap for germanium is —
a) 0.3 eV
b) 3.5 ev
c) 0.72 ev

The bandgap of silicon at room temperature is
a) 1.3 ev
b) 0.7 eV
c) 1.1 ev
d) L2/i
d) 1.1 ev
d) 1.4  

The earth wires are made of
a) Copper
b) Aluminium
c) Iron
d) Galvanized stranded steel

The rating of fuse is always expressed in —
a) Volts
b) Amperes
c) Ampere-volts
d) Ampere hours

48. A fuse is
a) Always connected in series with the circuit
b) Always connected in parallel with the circuit
c) Normally connected in series with the circuit
d) Normally connected in parallel with the circuit

The size of conductor used in power cables depends on
a) Operating voltage
b) Power factor
c) Current to be carried
d) Type of insulation used

Ohm's law is applied to —
a) Semiconductors
b) Electrolytes
c) Carbon resistors
d) All of these


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