Echoes are produced by
the reflection of sound waves
the refraction of sound waves
the interference of sound waves
reverberation of sound waves
Correct Answer :
A. the reflection of sound waves
Related Questions
The inability of a body to change its state of rest or uniform motion along a straight line is called its
momentum
velocity
acceleration
inertia
A star contains
about 75% of hydrogen
22% helium
traces of most other elements including oxygen, neon, carbon and nitrogen
All the above
A bullet is fired at a certain angle with the horizontal. Its path will be
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a straight line
a parabola
a vertical line
If a body weight 12N on the surface of the earth, how much will it weigh on the surface of the moon where acceleration due to gravity is only one-sixth of that on earth's surface?
12N
2N
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The number of galaxies that are visible without telescope on clear dark nights and away from bright lights is
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two
three
infinite
The brightest planet in the Solar System is
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The transistor was invented by
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John Bardeen, Walter H. Brattain and William Shockley
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Among the following the most suitable material for the core of an electro-magnet is
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raises the melting point of ice
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A radio set that uses valves does not start operating immediately when it is switched on whereas a set containing only tranaistors operates immediately. The reason for this is that
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valve-radio sets work at a higher voltage
transistor set has a low resistance
filaments of the valves cake time to beat up and function
A workman was working on a rail track. A young boy at a distance holds his ear close to the railway track. The boy was able to hear the sound of each blow or the workman twice. It is because
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speed of sound is greater in air than in steel
part of sound waves is reflected between rail tracks
the boy's ears are at a different distance from the source
At what temperature do the Fahrenheit and Celsius scales give the same reading?
212°
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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
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
Lightning conductors are made of
iron
chromium
copper
steel
Diamond shines because of its
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hardness
high density
high refractive index and low critical angle
Alternating Current (AC) is more advantageous than direct current because
it can be transmitted easily and efficiently
Alternating Current (AC) loses the least amount of energy when transmitted at high voltages
Alternating Current (AC) voltage can be easily increased or decreased
all the above
Heat is transmitted from one end of a metal rod to its other end by the method of
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convection
radiation
sublimation
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Nuclear fission process means
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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
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Bats flying in the dark avoid obstacles because
they can see very dearly only in darkness
they produce ultrasonic waves which guide them
their eyes are sensitive to darkness
their eye holes expand in darkness
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friction
elasticity
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a glass rod with flannel
an abonite rod with flannel
a glass rod with silk
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gives it a more attractive appearance
Both (a) and (b) above
None of the above
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kinetic energy
momentum
impulse
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area of the exposed surface of the liquid
temperature of air and of the liquid
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