Among the following the most suitable material for the core of an electro-magnet is
steel
wood
soft iron
copper
Correct Answer :
C. soft iron
Related Questions
Hot water is poured simultaneously in four metallic tumblers painted outside with different paints. After some time the water will be found to have cooled most in the tumbler painted.
rough white
rough black
shining white
shining black
The principle of equivalence of mass and energy was established by
Dalton
Rutherford
Einstein
Planck
The cover of a solar cooker is made of glass because
it absorbs sun's rays
it reflects sun's rays
it retains the heat inside by the greenhouse effect
it radiates heat better than metals
The force that keeps a body in a circular motion la called
the centripetal force
the centrifugal force
the frictional force
All the above
The number of galaxies that are visible without telescope on clear dark nights and away from bright lights is
one
two
three
infinite
The colour or an opaque object is due to the colour it
absorbs
refracts
reflects
scatters
If a band is played on the moon the sound will
reverberate
be heard by us faintly
be heard upto 10 km from it
not be heard at any distance at all from it
A balloon ruled with hydrogen will
continue going upwards uninterrupted
reach a particular height and remain floating
burst after reaching some height
reach a particular height and start coming down
Water has maximum density at
0° C
-15° C
4° C
15° C
The barometer was invented by
Michael Faraday
Torricelli
Thomas Alva Edison
Benjamin Franklin
The planet that spins Caster than any other planet is
Saturn
Jupiter
Earth
Mercury
The red colour of the setting sun is due to
the least scattered red colour reaching the eye
the dispersion of sun light occurred in air molecule in atmosphere
the diffraction of sunrays in atmospheric layers
interference of all the rays coming from the sun
Lightning is produced when
similar charges of electricity rush towards each other and then get repelled
clouds strike against impurities in air and the friction burns up these impurities
strong opposite charges in different clouds break down the resistance offered by the intervening air
water vapour produces electricity in the clouds
The instrument used to determine the RD (Relative Density) of a liquid by the principle of floatation is
Hygrometer
Hypsometer
Hydrometer
Densimeter
A person cups his hand around the mouth when shouting. Why?
Sound energy from his mouth is then directed in one direction
The cupped hand acts as a cardboard tube of short length
The pitch of sound increases
Both (a) and (b)
Powder clings to the skin because of
cohesion
adhesion
capillary action
absorption
The Milky Way is
the path of a star which is nearest to the earth
a galaxy which includes the sun
a star that is nearest to the earth
None of these
Of the following which has got the highest frequency?
ultraviolet rays
gamma rays
radio waves
infrared waves
The brightest planet in the Solar System is
Jupiter
Mercury
Venus
Sirius
Which is the densest planet of the solar system?
Sun
Jupiter
Mercury
Earth
When an incident beam of light strikes the surface of a glass slab normally, the refracted beam
goes straight through without bending
gets deviated away from the normal
gets bent towards the normal
gets reflected
A man weighing 50 kg floats on water in a lake. His apparent weight is
50 kg
45 kg
zero
150 kg
A proton is
the ionised hydrogen molecule
the nucleus of helium atom
the nucleus of hydrogen atom
the positive counterpart of electron
When an electric apparatus is fitted with a three core flexible lead the insulation on the three wires is distinctively coloured. The present international convention is
brown for earth, yellow for live, light blue for neutral
green for earth, yellow for live, brown for neutral
yellow for earth, green for live, brown for neutral
brown or red for live, light blue or black for neutral and green or yellow for earth
The principle of equivalence of mass and energy was established by
Dalton
Rutherford
Einstein
Planck
On applying a constant force to a mass, It moves with a uniform
velocity
momentum
acceleration
angular velocity
In very cold countries alcohol is used as a thermometric liquid because
alcohol is a poor conductor of heat
alcohol can be coloured for its level to be seen easily
its freezing point is very low
it will not stick to the glass tube
Moon has no atmosphere because
it has no population
it is quite far off
its surface is full of rocks
its gravity is not sufficient for any atmosphere to hold on to it
On the Kelvin scale, the melting point of ice is
0 K
273 K
373 K
100 K
The pressure of air at high altitude is less than the atmospheric pressure at the sea level. Hence the boning point of water at a hill top
is more than at sea level
is equal to that sea level
is less than at sea level
depends on the surrounding temperature