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
Which of the following has the highest refractive index?
Crown glass
Water
Flint glass
Diamond
The period of oscillation of a simple pendulum depends upon
the mass of its bob
the material of the bob
the amplitude of vibration
acceleration due to the gravity at the site of experiment
A boat loaded with rocks floats in the middle of a swimming pool. A man in the boat throws the rocks overboard. The level of water in the pool will
increase
decrease
remain the same
first decrease and then increase
A bar magnet tied in the middle with a thread is suspended at the South Pole of the earth. The magnet will be in
a horizontal position
a nearly vertical position with its South Pole downwards
a nearly vertical position with its North Pole downwards
a slanting position
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
Cosmic rays contain
protons and electrons
alpha particles
gamma rays
All the above
Before the invention of geostationary satellites, television stations could not transmit their programmes to far off places because
these signals are electromagnetic in nature
these are not electromagnetic in nature
their wavelength is very large
they are not reflected by the ionosphere but pass through it
The period of oscillation of a simple pendulum depends upon
the mass of its bob
the material of the bob
the amplitude of vibration
acceleration due to the gravity at the site of experiment
A timer in a race is at the finish line. He should start his stop watch
as soon as he hears the report of the gun
the moment he sees the flash
either (a) or (b) since that makes no difference
None of the above
The theory that the earth constituted the centre of the universe around which the sun and the planets revolved was propounded by
Copernicus
Ptolemy
Newton
Kepler
If a body is taken from the earth to the moon
both its mass and weight will be different
its mass will be different but the weight will remain the same
its mass and weight will both remain unchanged
its mass will remain the same but weight will be different
Which of the following is fissionable?
U-234
U-235
U-238
Both (b) and (c)
The period of a geostationary (synchronous) satellite orbiting the earth over the equator la
16 hours
12 hours
20 hours
24 hours
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
Of the following types of electromagnetic radiation which has the longest wavelength?
ultraviolet rays
gamma rays
radio waves
infrared waves
Which of the following is wrongly matched?
electric current - ampere
resistance - Ohm
electric power - volt
electric charge Coulomb
The coil of an electric heater is made of
Platinum
Tungsten
Nichrome
Copper
A bucket of water is hung from a spring balance. A piece of iron is suspended in the water without touching the sides or touching the bottom of the bucket. The reading of the spring balance
will increase
will decrease
does not change
varies with the increase of depth of the immersion of the iron piece
Of the following which has got the highest frequency?
ultraviolet rays
gamma rays
radio waves
infrared waves
Alternating Current (AC) is more advantageous than direct current because
it can be transmitted easily and efficiently
Alternating Current (AC) loses the least amount of energy when transmitted at high voltages
Alternating Current (AC) voltage can be easily increased or decreased
all the above
The plants in a greenhouse are enclosed in a glass enclosure because
glass allows the heat radiations of shorter wavelengths from the sun to pass through
the plants absorb them - these shorter wavelengths - and reradiate them in the form of longer wavelengths
the longer wavelengths cannot penetrate through the glass walls
All the above
The instrument used to determine the RD (Relative Density) of a liquid by the principle of floatation is
Hygrometer
Hypsometer
Hydrometer
Densimeter
The following are the atmospheric zones above the surface of the earth:
A) Troposphere
B) Ionosphere
C) Stratosphere
D) Exosphere
Select the correct sequence from the earth's surface on the basis of the codes given below:
ACBD
ABCD
CABD
BACD
Echoes are produced by
the reflection of sound waves
the refraction of sound waves
the interference of sound waves
reverberation of sound waves
Which of the following apparatus is used in the electrolysis of water?
Voltmeter
Voltameter
Ammeter
Potentiometer
A stationary elevated object has
kinetic energy
potential energy
momentum
both potential and kinetic energy
One can be recognised by his voice alone due to the factor of
quality
amplitude
pitch
loudness
In the visible spectrum which colour has the shortest wavelength?
Red
Blue
Yellow
Violet
Chronometer la an instrument to measure
heat
electric potential
time
distance between two points
In compact porous soil, the rising of the water is due to
capillarity
cohesion
adhesion
viscosity