Laser is a device to produce
Gamma rays
Microwaves
A beam of white light
A beam of coherent light
Correct Answer :
D. A beam of coherent light
Related Questions
The friction factor for the turbulent fluid flow in a rough pipe does not depend upon the
Pipe roughness & pipe diameter
Fluid velocity
Type of flowing fluid
Both 'b' & 'c'
Diamagnetic materials
Are magnetised by eddy currents only
Are non-magnetic and cannot be magnetised
Are magnetised in direction opposite to the magnetic field
Can be magnetised in one direction only
The most detrimental impurity in high pressure boiler feed water is
Suspended salt
Dissolved salt
Silica
Turbidity
Which of the following is used to produce draught in the locomotive boilers?
Chimney
Induced draught fan
Forced draught fan
Steam jet arrangement
A highly elastic material is deformed least on loading and retains its original form on removal of the load. Which of the following is the most elastic material?
Steel
Glass
Rubber
Brass
Vibration upto 100 kilo hertz can be most accurately measured by a __________ type accelerometer.
Preloaded spring
Piezoelectric
Bonded strain gauge
None of these
Minimum number of members required to form a Public Limited Joint Stock Com-pany is
7
10
12
17
Steel containing low percentage of nickel, chromium & tungsten are termed as the __________ steel.
Wrought
Tool
Alloy
Plain carbon
Which of the following relationships is correct for relating the three elastic constants of an isotropic elastic material (where, E = Young's modulus, G = Modulus of rigidity or shear modulus v = Poisson's ratio)?
E = 2G (1 + v)
E = G (1 + v)
E = G (1 + v)/2
E = 2G (1 + 2v)
Pick out the wrong statement.
The equivalent stiffness of two springs (of equal stiffness 'S') in series is S/2 while in parallel is 2S
For a helical spring, deflection is proportional to D3 (D = mean coil diameter) or d4 (d = wire diameter)
Crushing load or columns is less than the buckling load
Modulus of resilience is proportional to (stress at elastic limit)2
Which of the following low melting alloy containing bismuth and lead is used for electric fuse?
Wood's metal
Babbitt metal
Monel metal
Duralumin
Which of the following is not a characteristic observed in material failure by fatigue fracture?
Plastic deformation of material does not occur
Initiation of crack from below the surface does not occur
Initiation of crack occurs on the surface of the machine part
Presence of both rough & smooth zone with conchoidal markings in smooth zone of the surface
The same volume of all gases is representative of their
Specific gravities
Densities
Gas characteristic constants
Molecular weights
Hooke's law
Applies to elastic deformation
Applies beyond limit of proportionality in stress-strain curve
States that stress is inversely proportional to strain upto elastic limit
None of these
Steam condenser tubes are made of admiralty brass, in which percentage of zinc & copper are __________ respectively.
70 & 30
30 & 70
50 & 50
90 & 10
Heat flow across a hollow sphere of inner radius 'r1' and outer radius 'r2' is directly proportional to
(r2 - r1)/r1. r2
r1. r2/(r2 - r1)
(r2 + r1)/r1. r2
r1. r2/(r2 + r1)
In chemical dehumidification process
Wet bulb temperature increases
Dry bulb temperature remains constant
Dew point temperature increases
Dry bulb temperature increases
The transition temperature at which all the ferromagnetic materials become paramagnetic materials is termed as the 'Curie temperature'. Its value for cobalt is __________ °C.
768
1127
1359
1480
Out of the following, the lowest packing of atoms exists in __________ crystal lattice structure.
Hexagonal close, packed (hcp)
Face centred cubic (fcc)
Body centred cubic (bcc)
Simple cubic
Difference at any instant between the value of the controlled variable and the set point is called the
Deviation
Derivative time
Error ratio
Differential gap
In inventory control theory, the economic order quantity (EOQ) is the
Lot size corresponding to break even analysis
Average level of inventory
Optimum lot size
None of these
The taper provided on pattern for its easy & clean withdrawal from the mould is termed as the __________ allowance.
Casting
Pattern
Draft
Distortion
Ceramic compounds as compared to metallic compounds
Crystallise faster
Resist greater tensile stress at room temperature
Have higher melting temperature
Are better conductor of electricity at higher temperature
Yield strength of a material is determined by the __________ test.
Creep
Tension
Compression
Endurance
The most important consideration in value engineering is the
Profit maximisation
Customer satisfaction
Cost reduction
Process improvement
Silicon percentage in silicon steel used for electrical equipments is about
1
4.0
8
14
Optical activity is a/an __________ property.
Additive
Constitutive
Both (A) & (B)
Neither (A) nor (B)
What is the value of included angle of a triangular notch for maximum discharge?
30°
60°
90°
120°
Insulation of liquid surface can be achieved by __________ on top of its surface.
Floating hollow polypropylene spheres
Spraying alumina powder
Putting cement
None of these
The difference between gross & net calorific values of fuel is due to the
Sensible heat carried away by the flue gases
Heat carried away by the steam from the moisture content of the fuel
Heat lost by radiation
Heat carried away by steam from the combustion of hydrogen in the fuel