The air inside an electric, bulb is removed to prevent
oxidation of the tungsten filament
bursting of the bulb
loss of light due to absorption
keeping the weight of the bulb less
Correct Answer :
A. oxidation of the tungsten filament
Related Questions
Out of the following, name the fluorescent substance.
quinine sulphate solution
paraffin oil
fluorescein solutions
All the above
A pressure gauge for fluids is called
a hydrometer
a manometer
a lactometer
an anemometer
Halley's comet appears in the heavens once in
40 years
50 years
76 years
80 years
The light from the star nearest to the sun reaches the earth in
8 minutes
4.3 years
12 seconds
24 hours
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
A boy is swinging a ball attached to a string in a horizontal circle. If the string snaps
the ball will travel towards the centre of the circle and fall down
it will continue to travel along a tangent to the circle at the point the ball was at the time of snapping and finally fall down
it will fall down at the same place where the string breaks
None of these
The barometer was invented by
Michael Faraday
Torricelli
Thomas Alva Edison
Benjamin Franklin
Isotones are species of atoms containing
same number of protons but different number of neutrons
same number of neutrons but different number of protons
the same total number of protons and neutrons
same number of protons and different number of electrons
The direction of heat flow between two objects depends on
their heat contents
their masses
their temperatures
whether they are in solid, liquid or gaseous state
The instrument used to measure atmospheric pressure is
Pyrometer
Eudiometer
Barometer
Hydrometer
When a body is immersed in a fluid the force of buoyancy of the fluid on the body depends on
the immersed volume of the body
density of the liquid
acceleration due to the gravity at the place
All the above
In a freezer ice cubes will be formed more quickly in trays made of
rubber
plastic
aluminium
wood
The function of a moderator in a nuclear reactor is
to absorb unwanted neutrons
to slow down the fast neutrons to secure more effective hits on other nuclei
to decrease the number of fissile nuclei
to increase the number of fissile nuclei
A man Jumping out of a moving train is thrown
forward
backward
sideways
None of the above
SONAR (Sound Navigation Ranging) is
used by warships and military aircraft to locate enemy submarines
used by ships to determine the depth of water beneath them
a detective device that uses sound to locate under - water objects
All the above
When a light ray is reflected repeatedly by a set of parallel plane mirrors, the intensity of light ray diminishes alter a few reflections. This is because of
poor reflection from the mirrors
scattering of light from the mirrors
absorption of some light by the mirrors
absorption of light by the atmosphere
Why is it cool near an open pond on a hot summer day?
Evaporation at the surface causes cooling
The heat obsorbed at the surface is passed on to the bottom
Because of impurity in the water
Because of convection currents set up inside water
A person does not sink in the Dead Sea because
the sea contains a large amount of other salts besides sodium chloride
the density of the person is less than the density of the Dead Sea water
of the surface tension due to salt water in the Dead Sea
of difference in mass
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
In an oil lamp, holes are provided below the chimney so that
necessary oxygen for burning of oil may be provided
the convection current of air may be maintained to keep the lamp burning
the brightness of the lamp may be increased
All the above
Thick brick walls are used in the construction or a cold storage because bricks
are good conductors of heat
are cheaper
are easily obtained
are bad conductors of heat
The transistor was invented by
Marconi
Baird
John Bardeen, Walter H. Brattain and William Shockley
Edison
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
When we sweat, we feel comfortable under a fan because
the air circulated by the fan is cool
the fan produces convection currents of air
the air circulated by the fan quickens the evaporation of the moisture on our skin
the air takes away the heat from our body
The world's first artificial satellite Sputnik I was launched by Russia in
1985
1957
1959
1960
Radio waves sent out by radio stations are reflected by
troposphere
stratosphere
mesosphere
ionosphere
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
The stars that shine brightly then dimly and then brightly are known as
meteors
binaries
variable stars
bright stars
A hydraulic brake in an automobile uses
a fluid to transmit the braking force
the force applied by the driver
hydrogen gas and not any liquid
a vacuum brake
The device used to record the sound is
a microphone
a headphone
a phonograph
an amplifier