Radio waves sent out by radio stations are reflected by
troposphere
stratosphere
mesosphere
ionosphere
Correct Answer :
D. ionosphere
Related Questions
Cosmic rays contain
protons and electrons
alpha particles
gamma rays
All the above
For an electron orbiting in a hydrogen atom, the necessary centripetal force keeping it in orbit is provided by
the electrical attraction between the negatively charged electron and the positively charged porton
the high speed of the electron
the low speed of the electron
gravity
When water is cooled from 4�C to 2�C its density
increases
decreases
remains the same
first increases then decreases
It is easier to climb down a staircase than climb up because in climbing down
work is done against gravity
the steepness of the staircase isn't felt
gravity assists
there is no friction between the legs and steps
Electron-volt is a unit of
power
velocity
energy widely used in nuclear physics
number of electrons
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
Which of the following is not electromagnetic waves?
heat waves
sound waves
radio waves
light waves
A timer in a race is at the finish line. He should start his stop watch
as soon as he hears the report of the gun
the moment he sees the flash
either (a) or (b) since that makes no difference
None of the above
Frictional force acts in
the same direction as the motion
the opposite direction of the motion
all the directions
upward direction
The Space Application Centre for training in Satellite Communication Technology is located at
Bangalore
Mumbai
Ahmedabad
New Delhi
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
Metals are good conductors of heat because
they contain free electrons
their atoms are relatively far apart
their atoms collide frequently
they have reflecting surfaces
A lactometer la used to
find out the specific gravity of liquids
measure the volumes of liquids
test the purity of milk
determine the strength of acid in car batteries
X-rays were discovered by
Wilhelm Roentgen
WO Coolidge
Henry Cavendish
William Watson
Which of the following has the highest refractive index?
Crown glass
Water
Flint glass
Diamond
When the resistance of a circuit increases the current will
increase
decrease
remain the same
None of the above
The period of a geostationary (synchronous) satellite orbiting the earth over the equator la
16 hours
12 hours
20 hours
24 hours
The force of attraction or repulsion between two charged bodies is directly proportional to the product of the charges and inversely proportional to the square of distance between them. This was propounded by
Coulomb
Gilbert
Volta
Rutherford
Mercury is used in thermometers because
it has high thermal conductivity
it has uniform expansivity
it has high boiling point and low freezing point
of all the above
When a bullet is fired from a gun
the gun moves forward
the gun jumps up
the gun does not move
the gun recoils with the same momentum as the bullet
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
Besides protons, the nucleus of an atom contains
electrons
neutrons
neutrons and electrons
electrons, neutrons and other particles
In the electrical circuit of a house the fuse acts as
a thermopile
a load
a step down device
a safety device
The instrument used to measure atmospheric pressure is
Pyrometer
Eudiometer
Barometer
Hydrometer
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
If an object is placed between two parallel plane mirrors, the number of images formed will be
1
infinite
0
4
If you want to open a door with les difficulty you push it
at the middle
at a point away from the hinge (near the rim)
near the hinge
None of the above
Acoustics is a property or
Physics
Chemistry
Biology
Economic
In the nucleus of an atom, the uncharged particle is
proton
neutron
electron
positron
If a man wants to hear clearly the echo of a sound produced by him from a hill, the hill should be away from him by a minimum distance of
330 m
33 m
16.5 m
165 m