181.
Which parameter does not change during transformation action in transformer?
A
Frequency
B
Current
C
None of these
D
Voltage
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Which parameter does not change during transformation action in transformer?
Frequency
Current
None of these
Voltage
The primary and secondary winding of transformer are linked each other by
mutual induction
not linked at all
self induction
conduction
As compared the transformer with AC machines it is more efficient because
it does not have copper losses
core losses negligible
none of above
it does not have mechanical losses
In transformer, humming sound occurs due to
load
magnetostriction
none of above
oil
When AC supply is given to the transformer, the flux will depend on
voltage
frequency
both voltage and frequency
current
Which of the following is not true?
Soft solder – lead-37%, tin-63%
Medium solder – lead-50%, tin-50%
Electrician solder – lead-64%, tin-36%
Plumber's solder – lead-70%, tin-30%
The composition of electrician solder is
lead-37%, tin-63%
lead-50%, tin-50%
lead-63%, tin-37%
lead-70%, tin-30%
The composition of soft solder is
lead-37%, tin-63%
lead-50%, tin-50%
lead-63%, tin-37%
lead-70%, tin-30%
In soldering the melting point of filler metal is
below 420°C
above 420°C
below 520°C
above 520°C
The commonly used flux in brazing is
Borax
Rosin
Lead sulphide
Zinc chloride
The filler metal used in brazing has melting point of above
200°C
300°C
420°C
520°C
A braze joint may be satisfactorily used on components made of.......
Tinplate
Brass
Copper
Aluminium
Spelter is same as......
Tin
Zinc
Lead
Silver
Heat for soldering process is supplied by.........
Soldering iron
Induction furnace
Electric resistance method
Any of the above
The commonly used flux for brazing is.......
Resin
NH4CL
Borax
Soft iron
The purpose of using borax in brazing is to......
Replace flux
Dissolve oxides when heating the work
Accelerate the formation of oxides on the work
Prevent the spelter from melting too quickly
Entrapped fluxes, during brazing result in.......
Presence of gas pockets
Corrosion
Cracking
Distortion of joints
The flux is brazing process is used in the form of.......
Powder
Liquid
Paste
Any of the above
Which of the following flux is used for brazing aluminium and magnesium.......
Mixture of boric acid,borax and wetting agent
Boric acid,borax or fluoride with a wetting agent
Chlorides and fluorides mixed with water
Any of the above
Brazing is the process of.......
Joining plastic sheets
Hard soldering using brass spelter
Casing in brass
Makeing steel look like brass