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
Correct Answer :
C. a glass rod with silk
Related Questions
A capillary tube is partially dipped vertically in a vessel containing water. Due to capillarity water rises in the tube. The height of water rise in the tube can be increased by
decreasing the radius of the capillary tube
increasing the radius of the capillary tube
increasing the height of water in the vessel
None of these
The rocket engine is motivated by jet propulsion which uses the famous
Kepler's Laws
Newtonian Third Law of Motion
Bernoulli's Principle
Law of Relativity
Photocells are used
in burglar alarms
in automotive devices for light switches
television cameras
All the above
When the resistance of a circuit increases the current will
increase
decrease
remain the same
None of the above
The largest reserve of radioactive element which can be used in a nuclear reactor has been found in India, The name of the element is
Thorium
Uranium
Plutonium
Radium
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
Cosmic rays contain
protons and electrons
alpha particles
gamma rays
All the above
The freezer in a refrigerator is placed near the top
to keep it away from the hot compressor which is near the bottom
because of convenience
so that it can cool the whole interior by setting up convection currents
to prevent too much cooling
Enriched uranium means
Uranium that is very pure
Uranium in which the concentration of the isotope U-238 is more than in the naturally occuring uranium
Uranium in which the concentration of the isotope U-235 is more than in the naturally occuring uranium
None of the above
Air escaping rapidly from a narrow orifice in an inflated tyre feels cool because
the speed with which it escapes cools it down
of the higher temperature of the surroundings
of sudden expansion causing loss of internal energy
there is no real fall in temperature
A ruse wire is characterised by
high resistance and high melting point
high resistance and low melting point
low resistance and high melting point
low resistance and low melting point
Water has maximum density at
0° C
-15° C
4° C
15° C
The method used to separate aluminium from a alumina is
electroplating
electrotyping
electrolysis
distillation
The number of galaxies that are visible without telescope on clear dark nights and away from bright lights is
one
two
three
infinite
One can be recognised by his voice alone due to the factor of
quality
amplitude
pitch
loudness
We always see only one side of the moon because
the sun comes in between the earth and moon
the moon is stationary
the time taken by the moon to rotate on its axis is the same as the time taken by it to revolve round the earth
moon revolves round the sun
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
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
The fact that two large ships travelling on close parallel courses in the same direction tend to move towards each other can be explained by
Bernoulli's principle
Magnetic properties of the ship's material
Newton's third law of motion
Earth's gravitational force
For detecting and, testing of small electric charges we use
an electrophorus
an electroscope
an electromagnet
an ammeter
A man weighing 50 kg floats on water in a lake. His apparent weight is
50 kg
45 kg
zero
150 kg
When are temperature resistance
increases
decreases
remains the same
first increases then decreases
Which part of the eye photographic camera?
Lens
Iris
Retina
Eyelid
Primary colours are
colours of the rainbow
colours in the spectrum of white light
colours which cannot be produced by mixing other colours
colours found in nature
Powder clings to the skin because of
cohesion
adhesion
capillary action
absorption
Diamond shines because of its
purity
hardness
high density
high refractive index and low critical angle
No current will flow between two charged bodies if they have the same
resistance
charge
potential
charge/potential ratio
Pieces of camphor placed on water move about rapidly. This is because of
diffusion
viscosity
surface tension
capillarity
Rain drops acquire spherical shape due to
viscosity
surface tension
friction
elasticity
In the fuse of an electrical installation blows out
replace the fuse by a thin wire
replace the fuse by a thick copper wire
replace the fuse by a fuse wire of proper rating
replace the fuse by nichrome wire