Electromagnets are used in
the telephone ear piece
the telegraph
the electric bell
All the above
Correct Answer :
D. All the above
Related Questions
Formation of shadows can be explained by
rectilinear propagation of light
reflection
refraction
total internal reflection
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
The red colour of the setting sun is due to
the least scattered red colour reaching the eye
the dispersion of sun light occurred in air molecule in atmosphere
the diffraction of sunrays in atmospheric layers
interference of all the rays coming from the sun
To produce beats it is necessary to have two waves
travelling in opposite direction
of slightly different frequencies
of equal wavelength
of equal amplitude
The heating element often used in an electric iron is
copper
tungsten
mica
nichrome
Atoms which have the same atomic number but different mass numbers are called
isobars
isomers
isotones
isotopes
Acoustics' la a branch or study dealing with
historical sites
architecture
sound
trigonometry
When water is cooled from 4�C to 2�C its density
increases
decreases
remains the same
first increases then decreases
Which of the following pairs is not correct?
Television - Baird
Transistor ~ Shockley
Thermometer - Celsius
Barometer Torricelli
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
Powder clings to the skin because of
cohesion
adhesion
capillary action
absorption
X-rays are used
in hospital in the treatment of malignant growth
to reveal hidden flaws in metal castings and welded joints
to detect alterations made in works of art
All the above
The acoustical quality of a room depends on
the size and shape of the room
the ability of the ceiling, walls and floor to exclude unwanted sound
the use of furnishings made of sound absorbing materials
All the above
The cover of a solar cooker is made of glass because
it absorbs sun's rays
it reflects sun's rays
it retains the heat inside by the greenhouse effect
it radiates heat better than metals
The planet that has got a well-developed set of rings is
Venus
Saturn
Mercury
Earth
The inside of both the walls of a thermos flask is silvered i.e., on the vacuum side in order to reduce heat loss by
convection
radiation
conduction
All the three
The scientist who first sent electromagnetic waves to distant places was
James Clerk Maxwell
Heinrich Hertz
Thomas Alva Edison
Baird
A capillary tube is partially dipped vertically in a vessel containing water. Due to capillarity water rises in the tube. The height of water rise in the tube can be increased by
decreasing the radius of the capillary tube
increasing the radius of the capillary tube
increasing the height of water in the vessel
None of these
The end product in the uranium disintegration series is
lead
zinc
carbon
tin
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
Warm air will hold more water vapour than cold air because
it is lighter
it has more water vapour in it
its molecules are close together
its molecules are far apart
A sensitive instrument susceptible to magnetic infiuence can be protected from external magnetic field by
enclosing it in a thick walled iron box
wrapping it with an insulator
by placing it inside a glass case
by surrounding it with fine copper gauze
In the fuse of an electrical installation blows out
replace the fuse by a thin wire
replace the fuse by a thick copper wire
replace the fuse by a fuse wire of proper rating
replace the fuse by nichrome wire
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
The force of attraction or repulsion between two charged bodies is directly proportional to the product of the charges and inversely proportional to the square of distance between them. This was propounded by
Coulomb
Gilbert
Volta
Rutherford
When the disturbed electrons of an exited atom transfer back into lower energy levels they emit energy in the form of electromagnetic wave pulses called
neutrons
electrons
phonons
photons
The filament used in the electric lamp is made of
nichrome
tungsten
copper
aluminium
The aneroid barometer uses
mercury
distilled water
alcohol
does not use any liquid
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
It is more difficult to walk on ice than on a concrete road because
there is very little friction between the ice and feet pressing it
ice is soft when compared to concrete
there is more friction between the ice and feet
None of the above