Dioptre is the unit of power of
convex mirrors
concave mirrors
concave lenses
lenses irrespective of types
Correct Answer :
D. lenses irrespective of types
Related Questions
Air escaping rapidly from a narrow orifice in an inflated tyre feels cool because
the speed with which it escapes cools it down
of the higher temperature of the surroundings
of sudden expansion causing loss of internal energy
there is no real fall in temperature
Photoelectric cell is a device which converts
light energy into electrical energy
electrical energy into light energy
magnetic energy into electrical energy
electrical energy into mechanical energy
The frequency of an ultrasonic wave is
the same as that of an audible sound
above the audible range
below the audible range
None of the above
When we tighten the string of a sitar or tanpura its pitch
remains the same
increases
decreases
None of the above
A ruse wire is characterised by
high resistance and high melting point
high resistance and low melting point
low resistance and high melting point
low resistance and low melting point
Holography is the technique of
taking photos of various objects
recording and reproducing three dimensional images
tracing out planets and stars in the sky
transmitting light waves
The loudness of a sound is determined by
Frequency
Amplitude
Speed
Wavelength
The sun continuously produces an enormous amount of energy. This la due to
nuclear fission
nuclear fusion
chemical combustion
boiling
Credit for starting Space Science Research in India goes to
HJ Bhabha
SS Bhatnagar
V Sarabhai
CV Raman
Astigmatism, a structural defect of the eye, is due to
the eye lens being thin
the eye lens being thick
lack of symmetry in the curvature of the eye preventing rays of light from being brought to a common focus
the pupil being very small
We see the flash of lightning before hearing the thunder because
light travels very much faster than sound
sound travels faster than light
lightning occurs nearer than thunder
both travel at the same speed
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
Raindrops assume a spherical shape because or
adhesion
surface tension
gravitational force
atmospheric pressure from all sides
Air pressure is usually highest when the air is
warm and moist
cool and dry
warm and dry
cool and moist
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
Every action has an equal and opposite reaction is Newton's law of Motion
first
second
third
fourth
Bats flying in the dark avoid obstacles because
they can see very dearly only in darkness
they produce ultrasonic waves which guide them
their eyes are sensitive to darkness
their eye holes expand in darkness
The neutron, one of the constituent particles of which the nuclei of atoms are composed was discovered by
Irene Curie
W Bothe and H Becker
James Chadwick
Jean Joliot
In a river, the currents are fastest where the river la
wide and shallow
narrow and shallow
wide and deep
narrow and deep
A boy is swinging a ball attached to a string in a horizontal circle. If the string snaps
the ball will travel towards the centre of the circle and fall down
it will continue to travel along a tangent to the circle at the point the ball was at the time of snapping and finally fall down
it will fall down at the same place where the string breaks
None of these
The velocity of sound in air increases with
the rise of temperature
rise of its frequency
decrease in humidity
fall of temperature
Enriched uranium means
Uranium that is very pure
Uranium in which the concentration of the isotope U-238 is more than in the naturally occuring uranium
Uranium in which the concentration of the isotope U-235 is more than in the naturally occuring uranium
None of the above
A proton is
a quantum of light energy
a quantum of matter
a positively charged atomic particle
another name for positron
Commonly used safety fuse wire is made of
Tin
Lead
Nickel
An alloy of tin and lead
The rocket engine is motivated by jet propulsion which uses the famous
Kepler's Laws
Newtonian Third Law of Motion
Bernoulli's Principle
Law of Relativity
The Indian Satellite System used for domestic communications, television and meteorology is known as
INSAT
Bhaskara
Aryabhatta
All the above
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
Chronometer is an instrument to measure
heat
electric potential
time
distance between two points
Cosmic rays are
powerful X-rays falling on the earth from space
ultraviolet rays from the sun
gamma rays from radioactive minerals
very energetic radiation falling upon the earth from outer space consisting chiefly of charged particles
Which of the following rays has the highest penetrative power?
a -rays
� -rays
? -rays
X-rays