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
Correct Answer :
C. it retains the heat inside by the greenhouse effect
Related Questions
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
Which of the following wires of same dimensions offers least resistance to the ,flow of current?
copper
aluminium
silver
nichrome
The Indian Satellite System used for domestic communications, television and meteorology is known as
INSAT
Bhaskara
Aryabhatta
All the above
The velocity of sound in air increases with
the rise of temperature
rise of its frequency
decrease in humidity
fall of temperature
Like magnetic poles
attract each other
repel each other
neither attract nor repel
attract or repel depending upon the conditions
The largest reserve of radioactive element which can be used in a nuclear reactor has been found in India, The name of the element is
Thorium
Uranium
Plutonium
Radium
When temperature decreases, resistance of metals to flow of electricity
increases
decreases
neither increases nor decreases
first increases then decreases
The audible range of a normal human ear is frequencies ranging from
10000 to 20000 Hz
50 to 15000 Hz
20 to 20000 Hz
15 to 50000 Hz
Which mirror is used as a rear view mirror in Vehicles?
Parabolic
Convex
Concave
Plain
The earth's nearest neighbour in space is
the Sun
the Moon
the Venus
the Mars
On the Kelvin scale, the melting point of ice is
0 K
273 K
373 K
100 K
The solar wind is composed of
outward stream of protons and electrons on the surface of the sun during solar flares and sun-spot activity
plasma
ionized gas
All of these
The Space Application Centre for training in Satellite Communication Technology is located at
Bangalore
Mumbai
Ahmedabad
New Delhi
The scientist who first sent electromagnetic waves to distant places was
James Clerk Maxwell
Heinrich Hertz
Thomas Alva Edison
Baird
Which of the following can produce electricity?
resistor
thermocouple
light bulb
neon tube
In a refrigerator, the refrigerant is
Nitrogen
Oxygen
Chlorine
Freon
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
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
In a freezer ice cubes will be formed more quickly in trays made of
rubber
plastic
aluminium
wood
An electric charge is measured in
coulomb
ampere
volt
watt
When a charged rod is brought near a collection of small pith balls, the balls
will jump rapidly up and down for a short time
will remain unaffected
Both (a) and (b) above
It will produce electric shock
When a body is immersed in a fluid the force of buoyancy of the fluid on the body depends on
the immersed volume of the body
density of the liquid
acceleration due to the gravity at the place
All the above
Resistance is measured in
Volts
Amperes
ohms
coulombs
At what temperature do the Fahrenheit and Kelvin scales give the same reading?
212°
32°
-40°
0°
Velocity of sound in high altitudes is low because at such a height
the temperature is low
there is no air
the pressure is low
All the above
At what temperature do the Fahrenheit and Celsius scales give the same reading?
212°
32°
-40°
0°
If an empty cylinder Is half ruled with a liquid, Its centre of gravity is
shifted upwards
shifted downwards
shifted neither upward nor downward
shifted upward or downward depending on the density of the liquid
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 body has fallen from a height. Just before touching the pound it has
lost all its potential energy and gained an equivalent amount of kinetic energy
gained potential energy and lost kinetic energy
gained kinetic energy as well as potential energy
lost kinetic energy as well as potential energy
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