Photocells are used
in burglar alarms
in automotive devices for light switches
television cameras
All the above
Correct Answer :
D. All the above
Related Questions
The spectrum of white light can be studied by
a microscope
a telescope
a stereoscope
a spectroscope
Solar radiation is preferred to other sources of energy because
it is practically inexhaustible
it is the cheapest form of energy
it does not cause pollution
All of the above
It is difficult to bon potatoes at the top or a mountain because
the water available is hard
it is colder than at sea level
the potatoes become hard
the boiling point of water is lower at that height on account of low atmospheric pressure
A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because
the floor and carpet are at different temperatures
the stone conveys the heat away from the feet more rapidly than the carpet
the carpet is a better conductor of heat than the stone
the human body maintains a constant temperature
A hydraulic brake in an automobile uses
a fluid to transmit the braking force
the force applied by the driver
hydrogen gas and not any liquid
a vacuum brake
In the nucleus of an atom, the uncharged particle is
proton
neutron
electron
positron
The stem of a vibrating tuning fork is pressed against a sound box. Then
the loudness of the sound increases
the loudness remains the same
the loudness decreases
the sound suddenly stops
The fact that two large ships travelling on close parallel courses in the same direction tend to move towards each other can be explained by
Bernoulli's principle
Magnetic properties of the ship's material
Newton's third law of motion
Earth's gravitational force
Which of the following can produce electricity?
resistor
thermocouple
light bulb
neon tube
The Indian Space Research Organisation (ISRO) is located at
Thumba
Bangalore
Ahmedabad
New Delhi
Which physical quantity is measured in watts
power
kinetic energy
momentum
impulse
The velocity of sound in air increases with
the rise of temperature
rise of its frequency
decrease in humidity
fall of temperature
Hot water is poured simultaneously in four metallic tumblers painted outside with different paints. After some time the water will be found to have cooled most in the tumbler painted.
rough white
rough black
shining white
shining black
Diamond shines because of its
purity
hardness
high density
high refractive index and low critical angle
Lightning is produced when
similar charges of electricity rush towards each other and then get repelled
clouds strike against impurities in air and the friction burns up these impurities
strong opposite charges in different clouds break down the resistance offered by the intervening air
water vapour produces electricity in the clouds
When a particle in motion is acted upon by a force in a direction perpendicular to the direction of motion, the path followed by the particle will be
a straight line
an ellipse
a circle
a parabola
When the velocity of a body is halved
its momentum is halved
its kinetic energy is halved
its acceleration is halved
its potential energy is halved
The heat generated in a conductor carrying current is proportional to
the resistance
the square of the current flowing through it
the time the current flows
All the above
Photocells are used
in burglar alarms
in automotive devices for light switches
television cameras
All the above
A cup of hot coffee is placed on a metal table in a room. By which of the following methods does it lose heat?
conduction and convection only
conduction and radiation only
convection and radiation only
conduction, convection and radiation
Of the following types of electromagnetic radiation which has the longest wavelength?
ultraviolet rays
gamma rays
radio waves
infrared waves
A projectile is fired at an angle with the horizontal with a small velocity. Its horizontal range will be maximum when the angle with the horizontal is
0°
30°
45°
60°
The number of galaxies that are visible without telescope on clear dark nights and away from bright lights is
one
two
three
infinite
When two similar sources vibrate with slightly different frequencies, a regular rise and fall occurs in the loudness of tone. This phenomenon Is known as
doppler effect
beats
resonance
echo
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 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
Rays from the headlight of a motor car are rendered parallel by suitably using
a convex mirror behind it
a concave lens behind it
a concave mirror in front of it
a concave mirror behind it
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
Sound waves in air are
transverse
longitudinal
transverse and longitudinal
neither transverse nor longitudinal
The image formed by a plane mirror is
of the same size as the object
at the same distance behind the mirror as the object is in front of it
virtual and laterally inverted
All the above