In an oil lamp, holes are provided below the chimney so that
necessary oxygen for burning of oil may be provided
the convection current of air may be maintained to keep the lamp burning
the brightness of the lamp may be increased
All the above
Correct Answer :
D. All the above
Related Questions
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
Which part of the eye photographic camera?
Lens
Iris
Retina
Eyelid
The spectrum of white light can be studied by
a microscope
a telescope
a stereoscope
a spectroscope
Tea pots are highly polished
so that they may reflect thermal radiation from outside and minimise such radiation from them
so that they may absorb all radiation from outside
to make them attractive to look at
because they take high polish
A bolometer is used to measure
the quantity of heat energy in a body
thermal radiations quantitatively
high temperature
the intensity of sound
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
The mode of travel of heat energy from the sun across the empty space beyond the earth's atmosphere is known as
conduction
convection
radiation
absorption
The image of an object formed in a plane mirror
is real
is virtual
can be obtained on a screen
is slightly bigger than the object
Cosmic rays contain
protons and electrons
alpha particles
gamma rays
All the above
The enormous energy released in nuclear and thermonuclear reactions is due to conversion of
chemical energy into heat energy
mechanical energy into heat energy
protons into neutrons
mass into energy according to Einstein's equation
The method used to separate aluminium from a alumina is
electroplating
electrotyping
electrolysis
distillation
If you want to open a door with les difficulty you push it
at the middle
at a point away from the hinge (near the rim)
near the hinge
None of the above
The filament used in the electric lamp is made of
nichrome
tungsten
copper
aluminium
The rocket engine is motivated by jet propulsion which uses the famous
Kepler's Laws
Newtonian Third Law of Motion
Bernoulli's Principle
Law of Relativity
Rain drops acquire spherical shape due to
viscosity
surface tension
friction
elasticity
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
The transistor was invented by
Marconi
Baird
John Bardeen, Walter H. Brattain and William Shockley
Edison
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
During thunder storm you are travelling in a car. To protect yourself from the lightning you will have to
remain in the car
get out of the car and lie flat in the ground
abandon the car and take shelter under a nearby tree
touch the nearest electric pole
When temperature decreases, resistance of metals to flow of electricity
increases
decreases
neither increases nor decreases
first increases then decreases
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
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
Tea pots are highly polished
so that they may reflect thermal radiation from outside and minimise such radiation from them
so that they may absorb all radiation from outside
to make them attractive to look at
because they take high polish
When we tighten the string of a sitar or tanpura its pitch
remains the same
increases
decreases
None of the above
The maximum displacement of the particle in a mechanical wave motion is known as
amplitude
vibration
frequency
phase
Separating particles from a suspension is effected by
centrifugal force
frictional force
gravitational force
distillation
When light travels from one medium to another there is a change in its
velocity
wavelength
frequency
Both (a) and (b) above
Which of the following is not electromagnetic waves?
heat waves
sound waves
radio waves
light waves
The earth's nearest neighbour in space is
the Sun
the Moon
the Venus
the Mars
The study of astronomy include a
astrology
astrophysics
astrometry
Both (b) and (c) above