When light passes from air to glass, its velocity in glass
increases
decreases
remains unchanged
first decreases then increases
Correct Answer :
B. decreases
Related Questions
Which of the following pairs is not correct?
Television - Baird
Transistor ~ Shockley
Thermometer - Celsius
Barometer Torricelli
Formation of shadows can be explained by
rectilinear propagation of light
reflection
refraction
total internal reflection
In very cold countries alcohol is used as a thermometric liquid because
alcohol is a poor conductor of heat
alcohol can be coloured for its level to be seen easily
its freezing point is very low
it will not stick to the glass tube
When are temperature resistance
increases
decreases
remains the same
first increases then decreases
Choose the correct answer
Microphone converts sound energy into electrical energy.
Electric fan converts electrical energy into mechanical energy.
Battery converts chemical energy into electrical energy.
All the above
Which of the following is known as freon?
Liquid ammonia
Carbon tetrafluoride
Dichloro-difluoro-methane
Sulphur dioxide
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
The instrument used to determine the RD (Relative Density) of a liquid by the principle of floatation is
Hygrometer
Hypsometer
Hydrometer
Densimeter
The Cact that the compass needle does not point true north was observed first by
Sir Isaac Newton
Columbus
Archimedes
Thomas Alva Edison
When we tighten the string of a sitar or tanpura its pitch
remains the same
increases
decreases
None of the above
A pair of stars that revolve round each other is
a neutron star
a binary star
a dwarf star
a polar star
Which of the following has the highest refractive index?
Crown glass
Water
Flint glass
Diamond
The leader of the team who succeeded in constructing the first nuclear reactor (an atomic pile) in the world was
Albert Einstein
Enrico Fermi
HJ Bhabha
Sir Isaac Newton
In a refrigerator cooling is produced by
the ice that deposits on the freezer
the evaporation of a volatile liquid
None of the above
Both (a) and (b)
Nuclear fusion is a process in which
the atoms and molecules lose their identity
nucleus is split into fragments
the nuclear reaction between two light atomic nuclei results in the formation of a heavier nucleus with release of a large quantity of nuclear energy in the process
absorption of neutron by a nucleus
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
Air pressure is usually highest when the air is
warm and moist
cool and dry
warm and dry
cool and moist
The mass number and the atomic number of an element are X and Y respectively. The number oC neutrons in the atom of that element is
X
Y
X + Y
X Y
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
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
No current will flow between two charged bodies if they have the same
resistance
charge
potential
charge/potential ratio
The air inside an electric, bulb is removed to prevent
oxidation of the tungsten filament
bursting of the bulb
loss of light due to absorption
keeping the weight of the bulb less
The overhead wires supported by high towers in the grid system carry
alternating current of very high frequency
alternating current of very high voltage
a very large direct current
a high voltage direct current
The heat produced in a conductor due to the passage of a current through it is proportional to
the square of the current
the resistance of the conductor
the time for which the current flows
All the above
Ultrasonic waves are used
in medical and surgical diagnosis
in testing the quality of the linings and pads used in vehicles and aircraft brakes
to clean surgical instruments, jewellery and similar articles
All the above
The temperature, surface features, length of days and nights of a planet depend on
its atmosphere
its distance from the sun
its rotation
All the above
Which of the following pairs is not correct?
Television - Baird
Transistor ~ Shockley
Thermometer - Celsius
Barometer Torricelli
The unit of heat energy is
watt
degree
joule
erg
What is the minimum velocity required for a rocket to overcome earth's gravity and travel into space?
18 km/sec
11.2 km/ sec
21 km/ sec
35 km/ sec
When a body Is taken to the poles from the equator, Its weight becomes
greater
less
the same
None of these