The base of an electric iron is brightly polished mainly
to make it smooth and frictionless
to make it rust - proof
to reduce heat loss by radiation
to make it more durable
Correct Answer :
C. to reduce heat loss by radiation
Related Questions
The power of a lens is
equal to its focal length
equal to its radius of curvature
equal to the reciprocal of its focal length (in metres)
equal to twice its focal length
Powder clings to the skin because of
cohesion
adhesion
capillary action
absorption
In experiments on static electricity the standard method for obtaining small amounts of positive electricity is to rub
a glass rod with flannel
an abonite rod with flannel
a glass rod with silk
Any of the above
While crossing a suspension bridge, the soldiers are ordered to break steps because
the marching in steps will involve a big strain on them
the resonant vibrations caused by their marching can damage the bridge increasing the amplitude to dangerous proportions
the marching may obstruct other traffic
rumblings of their marching may disturb the surroundings
Solids have definite shapes. This is because
the forces of cohesion of the molecules within are very much less in them
the forces of cohesion are very large
the forces of adhesion are large
the forces of adhesion are less
No current will flow between two charged bodies if they have the same
resistance
charge
potential
charge/potential ratio
Which of the following can produce electricity?
resistor
thermocouple
light bulb
neon tube
The electroplating of a metallic article
protects the article from atmospheric corrosion
gives it a more attractive appearance
Both (a) and (b) above
None of the above
A series of east moving still pictures can be made to appear as a moving picture because the eye
can focus very rapidly as pictures change
is quicker than the brain
can see two images separated only if the interval' between seeing them is more than' one-tenth of a second
can shut out some of the light
Rays similar to X-rays but of smaller wave length that are given off by radioactive substances are
�± -rays
�² -rays
�³ -rays
Cosmic rays
Resistance is measured in
Volts
Amperes
ohms
coulombs
The force that keeps a body in a circular motion is called
the centripetal force
the centrifugal force
the frictional force
All the above
Meteors
look like falling stars
are really pieces of rock or metal
burn up as they shoot through the air
All the above
A man Jumping out of a moving train is thrown
forward
backward
sideways
None of the above
A cup of hot coffee is placed on a metal table in a room. By which of the following methods does it lose heat?
conduction and convection only
conduction and radiation only
convection and radiation only
conduction, convection and radiation
Why is nuclear fusion also known as thermonuclear reaction?
Fusion converts nuclear energy into heat
Fusion demands conditions of extremely high temperature to produce it
Fusion produces large amount of heat
Fusion reactions takes place in the sun
The resistance of a wire depends on
the material of the wire
the length of the wire
the cross section of the wire
All the above
Hydrophone is an instrument used
for measuring relative density of liquids
by ships to pass on messages
for determining the depth of ocean bottoms etc.
by deaf people to aid hearing
Increase in pressure
has no effect on the boiling point of a liquid
raises the boiling point of a liquid
lowers the boiling point of a liquid
increases the volume of a liquid
When the velocity of a body is halved
its momentum is halved
its kinetic energy is halved
its acceleration is halved
its potential energy is halved
The temperature of a large bucket-full of hot water (a few degrees below boiling point) is lower than a beaker full of boiling water. But
the hot water contains a much larger quantity of internal energy than the boiling water
the boiling water contains more quantity of internal energy than the warm water
both of them have got the same amount of internal energy.
nothing can be said definitely with the data given
Which metal is used in storage batteries?
Copper
Lead
Tin
Iron
To get 5 images of a single object one should have two plane mirrors inclined at an angle of
72°
60°
36°
90°
Which of the following is fissionable?
U-234
U-235
U-238
Both (b) and (c)
The enormous energy released in nuclear and thermonuclear reactions is due to conversion of
chemical energy into heat energy
mechanical energy into heat energy
protons into neutrons
mass into energy according to Einstein's equation
When water is cooled from 4�C to 2�C its density
increases
decreases
remains the same
first increases then decreases
The brightest planet in the Solar System is
Jupiter
Mercury
Venus
Sirius
A lightning conductor installed in a building
does not allow the lightning to fall on the building at all
drives away the charged clouds
forces the lightning to fall on other buildings near that building
conducts the electric charges to the ground when lightning strikes the building
The presence of impurities
lowers the melting point of ice
raises the melting point of ice
has no effect on the melting point of ice
may lower or raise the melting point depending upon the type of impurities
The tiniest of the stars belong to the group known as
Giant stars
White Dwarf stars
Neutron stars
Super-giant stars