A rheostat is used
to increase the current flow in a circuit
to decrease the current flow
to measure the flow of electric current
Either (a) or (b) above
Correct Answer :
D. Either (a) or (b) above
Related Questions
If the speed of the rotation of the earth increases the weight of a body
will increase
will decrease
will have no change
will either increase or decrease
The source of electric energy in an artificial satellite is
mininuclear reactor
a dynamo
a thermopile
solar cells
Increase in pressure
has no effect on the boiling point of a liquid
raises the boiling point of a liquid
lowers the boiling point of a liquid
increases the volume of a liquid
In which of the following will a piece of iron weigh most?
in air
in an atmosphere of oxygen
in an atmosphere of CO2
in vacuum
X-rays are
deflected by electric field
deflected by magnetic field
slightly deflected by electric field and magnetic field
not deflected by electric and magnetic fields
It is easier to climb down a staircase than climb up because in climbing down
work is done against gravity
the steepness of the staircase isn't felt
gravity assists
there is no friction between the legs and steps
A sensitive instrument susceptible to magnetic infiuence can be protected from external magnetic field by
enclosing it in a thick walled iron box
wrapping it with an insulator
by placing it inside a glass case
by surrounding it with fine copper gauze
If a band is played on the moon the sound will
reverberate
be heard by us faintly
be heard upto 10 km from it
not be heard at any distance at all from it
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
Sound waves
are electromagnetic waves
can easily pass through vacuum
are always transverse waves
require a material medium for propagation
Raindrops assume a spherical shape because or
adhesion
surface tension
gravitational force
atmospheric pressure from all sides
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 velocity of sound in air
increases as the square root of the absolute temperature
decreases with temperature
is independent of temperature
None of these
The earth's nearest neighbour in space is
the Sun
the Moon
the Venus
the Mars
Who first established the fact that the earth revolves round the sun?
Sir Isaac Newton
Kepler
Copernicus
Ptolemy
The stem of a vibrating tuning fork is pressed against a sound box. Then
the loudness of the sound increases
the loudness remains the same
the loudness decreases
the sound suddenly stops
We see the sun before it actually rises on the horizon. This is due to
refraction
reflection
total internal reflection
parallax
Electron-volt is a unit of
power
velocity
energy widely used in nuclear physics
number of electrons
The ballistic missile, Agni 11, tested by India has a maximum range of
1000 km
1500 km
2000 km
500 km
A timer in a race is at the finish line. He should start his stop watch
as soon as he hears the report of the gun
the moment he sees the flash
either (a) or (b) since that makes no difference
None of the 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 hydraulic brake in an automobile uses
a fluid to transmit the braking force
the force applied by the driver
hydrogen gas and not any liquid
a vacuum brake
The image of an object formed in a plane mirror
is real
is virtual
can be obtained on a screen
is slightly bigger than the object
Why is nuclear fusion also known as thermonuclear reaction?
Fusion converts nuclear energy into heat
Fusion demands conditions of extremely high temperature to produce it
Fusion produces large amount of heat
Fusion reactions takes place in the sun
The end product in the uranium disintegration series is
lead
zinc
carbon
tin
For detecting and, testing of small electric charges we use
an electrophorus
an electroscope
an electromagnet
an ammeter
The velocity of sound in air
increases as the square root of the absolute temperature
decreases with temperature
is independent of temperature
None of these
Tea pots are highly polished
so that they may reflect thermal radiation from outside and minimise such radiation from them
so that they may absorb all radiation from outside
to make them attractive to look at
because they take high polish
X-rays are
deflected by electric field
deflected by magnetic field
slightly deflected by electric field and magnetic field
not deflected by electric and magnetic fields
A bolometer is used to measure
the quantity of heat energy in a body
thermal radiations quantitatively
high temperature
the intensity of sound