Formation of shadows can be explained by
rectilinear propagation of light
reflection
refraction
total internal reflection
Correct Answer :
A. rectilinear propagation of light
Related Questions
In the visible spectrum which colour has the shortest wavelength?
Red
Blue
Yellow
Violet
A lactometer is used to
find out the specific gravity of liquids
measure the volumes of liquids
test the purity of milk
determine the strength of acid in car batteries
The presence of impurities
lowers the melting point of ice
raises the melting point of ice
has no effect on the melting point of ice
may lower or raise the melting point depending upon the type of impurities
The shadow below a tree has bright spots in it because
light comes through circular gaps between the leaves
the leaves are circular
the rays bend to form circular spots
the gaps between the leaves act as pin holes
The electroplating of a metallic article
protects the article from atmospheric corrosion
gives it a more attractive appearance
Both (a) and (b) above
None of the above
For detecting and, testing of small electric charges we use
an electrophorus
an electroscope
an electromagnet
an ammeter
When a body is projected upwards
the time for the upward journey and downward journey are the same
the upward journey takes more time
the downward journey takes more time
Can't be said
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
Rain drops acquire spherical shape due to
viscosity
surface tension
friction
elasticity
The barometer was invented by
Michael Faraday
Torricelli
Thomas Alva Edison
Benjamin Franklin
The period of a geostationary (synchronous) satellite orbiting the earth over the equator la
16 hours
12 hours
20 hours
24 hours
The best estimates of the age of the earth comes from the studies of
angle of inclination of the earth
changes in radio-active minerals in it
period taken by Sun's light to reach the earth
artificial satellites revolving round the earth
When an electric bulb breaks, there la an explosive sound. That is due to
the chemical reaction between the gases inside the bulb
the compressed gases inside rushing out suddenly
the air outside rushing in to fill the vacuum inside the bulb
None of the above
Which of the following rays has the highest penetrative power?
a -rays
� -rays
? -rays
X-rays
When we tighten the string of a sitar or tanpura its pitch
remains the same
increases
decreases
None of the above
The instrument used to determine the RD (Relative Density) of a liquid by the principle of floatation is
Hygrometer
Hypsometer
Hydrometer
Densimeter
An astronomical unit of distance is
a kilometre
light year
the average distance from the earth to the sun
None of the above
Dioptre is the unit of power of
convex mirrors
concave mirrors
concave lenses
lenses irrespective of types
The study of astronomy include a
astrology
astrophysics
astrometry
Both (b) and (c) above
The evaporation rate depends on
the nature of the liquid
area of the exposed surface of the liquid
temperature of air and of the liquid
All the above
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
Which physical quantity is measured in watts
power
kinetic energy
momentum
impulse
A bullet is fired at a certain angle with the horizontal. Its path will be
elliptical
a straight line
a parabola
a vertical line
When a body is partly or wholly immersed in a liquid the apparent loss of weight is equal to the weight of the liquid displaced by the submerged portion. This is known as
Pascal's law
Bernoulli's law
Archimedes' law
Boyle's law
At temperature near OK, (zero kelvin) metals such as lead and tin become
insulators
semiconductors
superconductors
condenser
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
The atmosphere gets heated up mainly by
direct sun's rays
radiation from earth's surface
radiogenic heat (resulting from radioactive decay)
cosmic rays coming from space
Besides protons, the nucleus of an atom contains
electrons
neutrons
neutrons and electrons
electrons, neutrons and other particles
A light year means
a unit of time
a unit of length
a year of no consequence
illumination throughout the year
A hunter on the ground wishes to shoot a bird on a tree at a distance with his rifle. He has to point the rifle
at the lower elevation than the bird
at a higher elevation than the bird
in the same direction as the bird
vertically upwards