The maximum range of most TV signals is from 121 to 240 km only because
the curvature of earth limits the range of reception
the signals are weak
the signals are absorbed by air
the antennae are not powerful enough
Correct Answer :
A. the curvature of earth limits the range of reception
Related Questions
Astigmatism, a structural defect of the eye, is due to
the eye lens being thin
the eye lens being thick
lack of symmetry in the curvature of the eye preventing rays of light from being brought to a common focus
the pupil being very small
One finds it more difficult to walk on ice than on a concrete road because
there is more friction on ice than on concrete surface
ice is soft and spongy while concrete is hard
the friction between ice and the feet is less than that between the concrete and the feet
None of them
The mode of travel of heat energy from the sun across the empty space beyond the earth's atmosphere is known as
conduction
convection
radiation
absorption
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
A permanent magnet may be demagnetised by
placing it inside a solenoid through which an alternating current is flowing
heating the magnet to redness and then allowing it to cool
dropping it several times or hammering it while lying east-west
All the above
The velocity required to place a vehicle in orbit round the moon is _________ that required to place it in orbit round the earth.
less than
greater than
equal to
greater than or equal to
Alpha particles are
electromagnetic radiations
helium nuclei
negatively charged particles
neutral particles
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
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
Choose the correct answer
Microphone converts sound energy into electrical energy.
Electric fan converts electrical energy into mechanical energy.
Battery converts chemical energy into electrical energy.
All the above
A star contains
about 75% of hydrogen
22% helium
traces of most other elements including oxygen, neon, carbon and nitrogen
All the above
How is it that Pluto is not always the farthest planet of the solar system?
Each planet becomes the farthest planet in its turn. Now it is the turn of Piuto
The Sun is now in the zodiac in which it is nearest to outer planets
The eccentricity of Piuto's orbit being substantial, this orbit cuts the orbit of Neptune
Piuto belongs to other solar system
The minimum velocity required by a satellite to escape earth's gravitational pull is
18 km/s
11.2 km /s
21 km/s
35 km/s
In the visible spectrum which colour has the shortest wavelength?
Red
Blue
Yellow
Violet
Changing of one element into another element is known as
transmutation
fission
fusion
radioactivity
Besides protons, the nucleus of an atom contains
electrons
neutrons
neutrons and electrons
electrons, neutrons and other particles
The filament lamp is an example for
fluorescence
incandescence
both (a) and (b)
None of these
The principle on which a Jet engine works is
conservation of mass
Newtonian law of action and reaction
conservation of angular momentum
None of the above
In a longitudinal wave, the direction of propagation of the wave is
the same as the direction of the vibrations of the vibrating body
at right angles to the direction of the vibrations of the vibrating body
Both (a) and (b) above
None of the above
A temperature below absolute zero for an ideal gas
cannot be attained experimentally
can be attained
is impossible
Does not exist at all
A tube light works on the principle of
chemical, heating and magnetic effects of electricity
discharge of electricity through gases
the action of ultraviolet radiation on certain fluorescent materials
Both (b) and (c) above
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)
The Cact that the compass needle does not point true north was observed first by
Sir Isaac Newton
Columbus
Archimedes
Thomas Alva Edison
The instrument used to measure the strength of electric current at a point is
Ammeter
Altimeter
Adrinometer
Anemometer
In a concert hall reverberation is controlled by
reduction of seating capacity in the hall
increase of sound intensity in the hall
lining the walls, with leather panels put on over a layer of sound absorbent glass fibre
by opening the doors and windows of concert hall
Nuclear fission process means
absorption of a neutron by a nucleus
breakup of the nucleus of a heavy atom into two nearly equal halves emitting two or three neutrons and releasing large amounts of nuclear energy in the process
the scattering of neutrons
formation of heavier nucleus
When ice just melts
there is no change in volume
there is no change in temperature
heat is given out
there is no change of state
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
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
The brightest star visible to the naked eye is
Sirius
Vega
Rigel
Proxima Centauri