ELECTRICAL ENGINEERING BITS-7

101.

The resistance of a conductor varies inversely as
 area of cross-section 

102.

The structure sensitive property of a super conductor is

 critical current density

103.

Which of the following motor is not suitable for frequent starting and stopping?
 resistance split phase motor 

104.

Conductance is reciprocal of
 resistance 

105.

The carbon percentage is least in

 wrought iron

106.

It is desirable to keep the arc length short in order to ________
 All of these 

107.

_____ is a  solder.

 Copper-zinc

108.

Range of accelerating factor is _____
 1.6 to 1.8 

109.

In case of three core flexible cable the colour of the neutral is

 blue

110.

Telecommunication lines are transposed to reduce the _____?
 radio interference in communication lines 

111.

The efficiency of a machine should be as ______ as possible to reduce the operating cost.

 high

112.

In which of the following applications variable speed operation is preferred ?

 Ceiling fan

113.

In a stable control system saturation can cause which of the following ?

 Low-level oscillations

114.

ACSR means ??
 Aluminium conductor steel reinforced 

115.

A load of 900 lbs is to be raised with a lift car weighting 855 lbs at a speed of 110 feet per minute, the over balance being 40 % and percentage efficiency 45 %. Find the horse power of the motor without counterweight

 150.

116.

Which of the following is exhibited by Root locus diagrams ?
 The poles of the transfer function for a set of parameter values 

117.

Induction furnaces are used for ______

 Heat treatment of casting.

118.

Which of the following devices should be used for accurate measurement of low D.C. voltage ?
 D.C. potentiometer 

119.

When the excitation of normally operating unloaded, salient pole synchronous motor suddenly gets disconnected, it continues to run as a _____?

 variable reluctance motor

120.

The conductivity of an extrinsic semiconductor with temperature
 increase 

121.

If the resistance of a conductor does not vary in accordance with Ohm's law it is known as
 non-linear conductor 

122.

An electric motor with constant output power will have a torque speed characteristics in the form of a _______?

 Straight line parallel to the speed axis.

123.

In a control system the output of the controller is given to
 final control element 

124.

Telecommunication lines are transposed to reduce the __________?
 radio interference in communication lines 

125.

In single phase rotary converter the number of slip rings will be

 two.

126.

In case of kiln drives, starting torque is ______ ?

 more than double of the running torque.

127.

Thermocouples are mainly used for the measurement of
 temperature 

128.

The type 0 system has ______ at the origin.

 no pole

129.

A differentiator is usually not a part of a control system because it

 increases input noise

130.

In heating the ferromagnetic material by induction heating, heat is produced due to
 due to hysteresis loss as well as eddy current loss takingplace in the charge 

131.

In conductors conduction of electricity takes place due to movement of
 electrons only 

132.

Commonly used instruments in power system measurement are

 induction

133.

________is a part of the human temperature control system.
 Perspiration system 

134.

Hot rolled sheets have ______ value of permeability

 low

135.

Candela is the unit of which?
 Luminous intensity. 

136.

Sum of the elements of row i equal to shunt admittances connected to bus i. If this summation is zero, indicates there is no___________?

 both of these

137.

Direction of the current in the compensating winding is________ to the direction of current in the armature conductors?
 exactly opposite 

138.

Which of the following is the poorest conductor of electricity ?

 carbon

139.

In thermal-electrical analogy charge is considered analogous to

 temperature

140.

An amplidyne can give which of the following characteristics ?
 Constant current, constant voltage and constant power 

141.

The rectifier instrument is not free from

 frequency error

142.

_________method of starting a three phase induction motor needs six terminals.
 Star-delta 

143.

For heating element high resistivity material is chosen to

 reduce the length of heating element

144.

Power transformers should be designed to have maximum efficiency
 at or near full load 

145.

The starting torque in case of centrifugal pumps is generally

 less than running torque

146.

Spark plug makes use of which of the following materials for insulation ?
 Porcelain 

147.

In the indirect resistance heating method, maximum heat-transfer takes place by

 radiation

148.

For measurement of mutual inductance we can use
 Heaviside bridge 

149.

Vacuum is created by which of the following?
 Both vacuum pump and ejector 

150.

A synchronous machine has P number of poles, find the relation between electrical angular momentum (ωe) and mechanical angular momentum (ωm)?

 ?e = P/2*?m

151.

The cold rolled grain oriented steel has ______ permeability in the direction of the grain orientation.
 maximum 

152.

Heat transfer by condition will not occur when

 temperatures of the two bodies are identical

153.

The cost of an induction motor will increase as

 horsepower rating increases but r.p.m. decreases

154.

The main advantage of dielectric heating is that ___________
 Heating occurs in teh material itself. 

155.

A perfect conductor has
 infinite conductivity 

156.

While selecting motor for an air conditioner which of the following characteristics is of great importance ?

 Noise

157.

_______directly converts temperature into voltage.
 Thermocouple 

158.

Addition of 0.3 to 4.5% silicon to iron _____ the electrical resistivity of iron.

 increase

159.

From a uniform light source of 300 c.p. there exists a plane surface 15 m below the value of illumination on the plane surface when the luminous flux rays are inclined at an angle of 30 to the surface is ____?

 1.53 lumens.

160.

In a synchronous motor torque or load angle δ ------------- with increase in load.
 increases 

161.

The speed of a locomotive is controlled by

 gear box

162.

You have to replace 1500 Q resistor in radio. You have no 1500 Q resistor but have several 1000 Q ones which you would connect
 two in parallel and one in series 

163.

The value of critical field below the transition temperature will

 increase

164.

In jaw crushers a motor has to often start against ______ load.
 heavy 

165.

The wheels of a train, engine as well as bogies, are slightly tapered to

 facilitate in taking turns

166.

ACSR means ________
 Aluminium conductor steel reinforced 

167.

With which of the following, a circuit breaker must be equipped for remote operation ?

 Shunt trip

168.

Carbon electrodes are not used in
 GLS lamps 

169.

Transformers
 can change the level of current and voltage but total power remains same 

170.

D.C. windings are

 always 2-layer type

171.

Capacitor fitted with ceiling / table fans is of the value of
 2 - 3 µF. 

172.

What is the highest possible speed by turbo alternators?
 3000 rpm 

173.

______is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ?

 Cast steel

174.

_______is used for heating non-conducting materials.
 Dielectric heating 

175.

Condition for zero voltage regulation is __________

 tanf = R/X

176.

For power transformers employed for arc furnace, it is desirable to arrnage the furnace and transformer in such a way that leads are ______?
 Shorter in length and placed close together. 

177.

In order that current should flow without causing excessive heating or voltage drop, the relay contacts should
 have all these properties 

178.

An induction wattmeter can be used for

 A.C. only

179.

Which of the following devices is necessarily required for automatic temperature control in a furnace ?

 Thermocouple

180.

The current zero interruption, in oil and air blast circuit breakers, is achieved by
 both lengthening of the gap and cooling and blast effect 

181.

The main function of a fuse is to

 prevent excessive currents

182.

Which of the following has the highest value of thermal conductivity ?

 Solid ice

183.

Materials exhibiting zero value of resistivity are known as ______ .
 superconductors 

184.

Transformers with a capacity of upto _____ have a cooling radiator system with natural cooling

 10 MVA

185.

The oscillation in a synchronous motor can be damped out by_____?
 providing damper bars in the rotor pole faces. 

186.

_________technique gives quick transient and stability response.

 Root locus

187.

Which of the following machine is invariably provided with forced ventilation?
 Hermetically sealed motor of refrigerator. 

188.

In ______ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft.
 large 

189.

Series motor is not suited for traction duty due to which of the following account ?

 Current surges after temporary switching off supply

190.

Transmission lines are transposed to reduce __________?
 interference with neighbouring communication lines 

191.

A voltage of about 200 V can be measured

 a D.C. potentiometer in conjunction with a volt ratio box

192.

Regenerative feedback implies feedback with
 positive sign 

193.

For which of the following locomotives the maintenance requirements are the least?
 Electric locomotives 

194.

In heating the ferromagnetic materials by induction heating, heat is produced owing to ______

 Hysteresis loss as well as eddy current loss occuring in the change.

195.

What should be the minimum depth (in metre)of cable trench to dug for laying of 1.1 kV?

 0.75.

196.

Due to which of the following fact, in India, aluminium is replacing copper ?
 Aluminium is available in plenty, cheaper and lighter than copper 

198.

Which of the following types of motor enclosure is safest ?

 Totally enclosed fan cooled

199.

The ABCD constants of a 3-phase transmission line are A = D = 0.8∠1°, B = 170∠85° Ω , C = 0.002∠90.4° ℧. The sending end voltage is 400 kV. The receiving end voltage under no load condition is __________

 500 kV