When a whistling engine approaches a person standing on the platform, the frequency or the note
appears to increase
appears to decrease
does not change at all
first increases then decreases
Correct Answer :
A. appears to increase
Related Questions
In a dynamo
mechanical energy is converted to light energy
mechanical energy is converted to heat energy
mechanical energy is converted to electrical energy
electrical energy is converted to mechanical energy
In the nucleus of an atom, the uncharged particle is
proton
neutron
electron
positron
A nuclear reactor is said to have become 'critical' when
it stops due to malfunctioning
it starts emitting dangerous radioactive radiations
it is shut down to avoid explosion
it is ready to produce controlled energy
In the ramous equation of Einstein E = mc2 , 'c' denotes.
velocity of sound
velocity of light
a constant factor
wavelength of light
A light year means
a unit of time
a unit of length
a year of no consequence
illumination throughout the year
Photo-electric cells convert
electrical energy into light energy
light energy into electrical energy
light energy into heat energy
electrical energy into heat energy
The rate of cooling of a hot body depends on
the nature of the radiating surface
area of the radiating surface
temperature difference between the body and the surroundings
All the above
A small bubble of air deep down in a lake rises up to the top of the lake. The volume of the bubble on coming up will
increase
decrease
will not change
first increase and then decrease
Of the following which has got the highest frequency?
ultraviolet rays
gamma rays
radio waves
infrared waves
The colour or an opaque object is due to the colour it
absorbs
refracts
reflects
scatters
Changing of one element into another element is known as
transmutation
fission
fusion
radioactivity
The presence of impurities
lowers the melting point of ice
raises the melting point of ice
has no effect on the melting point of ice
may lower or raise the melting point depending upon the type of impurities
The transistor was invented by
Marconi
Baird
John Bardeen, Walter H. Brattain and William Shockley
Edison
A man Jumping out of a moving train is thrown
forward
backward
sideways
None of the above
The velocity of sound in air
increases as the square root of the absolute temperature
decreases with temperature
is independent of temperature
None of these
When a body is projected upwards
the time for the upward journey and downward journey are the same
the upward journey takes more time
the downward journey takes more time
Cant be said
When a body Is taken to the poles from the equator, Its weight becomes
greater
less
the same
None of these
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
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)
Which of the following wires of same dimensions offers least resistance to the ,flow of current?
copper
aluminium
silver
nichrome
When the earth reaches its perihelion
it is nearest to the moon
it is nearest to the sun
it is nearest to Pluto
it is farthest from the sun
Resistance is measured in
Volts
Amperes
ohms
coulombs
The instrument used to measure atmospheric pressure is
Pyrometer
Eudiometer
Barometer
Hydrometer
When a ship floats on water, the weight or water displaced is
an indeterminate quantity
equal to the weight of the ship
greater than the weight of the ship
less than the weight of the ship
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
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
Air pressure is usually highest when the air is
warm and moist
cool and dry
warm and dry
cool and moist
The method used to separate aluminium from a alumina is
electroplating
electrotyping
electrolysis
distillation
The aneroid barometer uses
mercury
distilled water
alcohol
does not use any liquid
The orbit of Venus lies between those of
Mercury and Earth
Earth and Mars
Mars and Saturn
Mars and Jupiter