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
Correct Answer :
B. they produce ultrasonic waves which guide them
Related Questions
The temperature, surface features, length of days and nights of a planet depend on
its atmosphere
its distance from the sun
its rotation
All the above
When an incident beam of light strikes the surface of a glass slab normally, the refracted beam
goes straight through without bending
gets deviated away from the normal
gets bent towards the normal
gets reflected
Rays similar to X-rays but of smaller wave length that are given off by radioactive substances are
a -rays
� -rays
? -rays
Cosmic rays
The motion .of the pendulum of a wall clock is an example of
linear motion
vibratory motion
rotational motion
None of the above
A transformer
converts direct current into alternating current
converts alternating current into direct current
steps up or steps down a given alternating current voltage
supplies current with zero resistance
For accurate scientific work, temperatures are often measured by
mercury thermometers
alcohol thermometers
platinum resistance thermometers
thermoelectric thermometers
The hygrometer is an apparatus used for finding the
temperature of air
intensity of light
density of a liquid
relative humidity of the atmosphere
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
While crossing a suspension bridge, the soldiers are ordered to break steps because
the marching in steps will involve a big strain on them
the resonant vibrations caused by their marching can damage the bridge increasing the amplitude to dangerous proportions
the marching may obstruct other traffic
rumblings of their marching may disturb the surroundings
Dioptre is the unit of power of
convex mirrors
concave mirrors
concave lenses
lenses irrespective of types
A pair of stars that revolve round each other is
a neutron star
a binary star
a dwarf star
a polar star
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
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
The ozone layer absorbs
Cosmic rays
Infrared rays
All radiations of light
Ultra violet rays coming from the sun
A device used in a ship for the purpose of measuring the depth of the sea is
an altimeter
a fathometer
a hydrometer
a sonometer
The transistor was invented by
Marconi
Baird
John Bardeen, Walter H. Brattain and William Shockley
Edison
Acoustics is a property or
Physics
Chemistry
Biology
Economic
The aneroid barometer uses
mercury
distilled water
alcohol
does not use any liquid
The filament lamp is an example for
fluorescence
incandescence
both (a) and (b)
None of these
The coil of an electric heater is made of
Platinum
Tungsten
Nichrome
Copper
X-rays were discovered by
Wilhelm Roentgen
WO Coolidge
Henry Cavendish
William Watson
The heat produced in a conductor due to the passage of a current through it is proportional to
the square of the current
the resistance of the conductor
the time for which the current flows
All the above
An ohm is a unit of
potential difference
resistance
current
All the above
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
The number of galaxies that are visible without telescope on clear dark nights and away from bright lights is
one
two
three
infinite
A bolometer is used to measure
the quantity of heat energy in a body
thermal radiations quantitatively
high temperature
the intensity of sound
Sound waves in air are
transverse
longitudinal
transverse and longitudinal
neither transverse nor longitudinal
The Indian Space Research Organisation (ISRO) is located at
Thumba
Bangalore
Ahmedabad
New Delhi
Skating on ice is possible because
the surface of ice is smooth
ice is cold
the pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water
the pressure on the ice due to skate raises its melting point
The speed of light is minimum while passing through
air
glass
vacuum
water