The radius of curvature of a spherical mirror is
equal to half its focal length
equal to its focal length
twice its focal length
not related to its focal length
Correct Answer :
C. twice its focal length
Related Questions
The radius of curvature of a spherical mirror is
equal to half its focal length
equal to its focal length
twice its focal length
not related to its focal length
The rings of Saturn were discovered by
Galileo
Bhaskara
Aryabhatta
Ptolemy
When an electric bulb breaks, there is 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
The electrical domestic tube light gives white fiourescent light because of
collision between molecules of filled gas under electric current
heavy current
vacuum inside the tube
falling of ultra violet rays on the white inner coating of the tube
A car parked in the sun with its windows closed gets terribly hot inside. This is due to
the heat emitted by the engine
the greenhouse effect
the good conducting power of the metal body
the double layered wind shield
We see the sun before it actually rises on the horizon. This is due to
refraction
reflection
total internal reflection
parallax
Who discovered that the Cree Call acceleration Is the same for any object at a given place?
Newton
Pascal
Archimedes
Galileo
When the resistance of a circuit increases the current will
increase
decrease
remain the same
None of the above
Chronometer la an instrument to measure
heat
electric potential
time
distance between two points
Out of the following which element has the longest half-life period?
Radium
Radon
Uranium-238
Plutonium
A hydrogen bomb is based on
nuclear fusion
nuclear fission
Both (a) and (b) above
Neither (a) nor (b)
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
Pyrometers are instruments used
for measuring the velocity of wind
in the manufacture of fireworks
in finding the coefficient of apparent expansion of a liquid
for measuring high temperatures
Separating particles from a suspension is effected by
centrifugal force
frictional force
gravitational force
distillation
The Milky Way is
the path of a star which is nearest to the earth
a galaxy which includes the sun
a star that is nearest to the earth
None of these
The base of an electric iron is brightly polished mainly
to make it smooth and frictionless
to make it rust - proof
to reduce heat loss by radiation
to make it more durable
When one enters a dark room after being in bright light one is not able to see anything clearly for a while because
the retina of the eye moves forward
the retina of the eye moves backward
c).the iris is unable to dilate the pupil immediately to be able to see things
the eye has no power of accommodation
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
It is more difficult to walk on ice than on a concrete road because
there is very little friction between the ice and feet pressing it
ice is soft when compared to concrete
there is more friction between the ice and feet
None of the above
The number of galaxies that are visible without telescope on clear dark nights and away from bright lights is
one
two
three
infinite
Galaxies emit
radio waves and X-rays
ultraviolet light waves
visible light waves
All the above
If an object is placed between two parallel plane mirrors, the number of images formed will be
1
infinite
0
4
The acoustical quality of a room depends on
the size and shape of the room
the ability of the ceiling, walls and floor to exclude unwanted sound
the use of furnishings made of sound absorbing materials
All the above
When light travels from one medium to another there is a change in its
velocity
wavelength
frequency
Both (a) and (b) above
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
Which of the following revolves round the nucleus in an atom?
protons
electrons
neutrons
positrons
Dioptre is the unit of power of
convex mirrors
concave mirrors
concave lenses
lenses irrespective of types
Out of the following which is an insulator?
Silver
Copper
Nichrome
Dry wood
Cyclotron is an apparatus used
as an accelerator for imparting energies to charged particles of atomic magnitudes
to reduce the charge on a particle
to produce intense magnetic field
to produce intense electrical field
The escape velocity of a satellite projected from the surface of the earth is independent of
the mass of earth
the mass of the satellite
the radius of the earth
gravitation of the earth