The strength of an electromagnet can be increased by
increasing the length of the coiled wire
increasing current supply
increasing the size of the iron core
All the above
Correct Answer :
D. All the above
Related Questions
A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is
greater than the weight of the man
less than the weight of the man
same as the weight of the man
zero
Water has maximum density at
0° C
-15° C
4° C
15° C
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
Match the following:
| A. Manometer | 1. Depth of sea |
| B. Audiometer | 2. High temperatures |
| C. Pyrometer | 3. Level of human hearing |
| D. Fathometer | 4. Pressure of a gas |
A-1 B-4 C-3 D-2
A-4 B-3 C-1 D-2
A-4 B-3 C-2 D-1
A-3 B-4 C-1 D-2
During thunder storm you are travelling in a car. To protect yourself from the lightning you will have to
remain in the car
get out of the car and lie flat in the ground
abandon the car and take shelter under a nearby tree
touch the nearest electric pole
When an incident beam of light strikes the surface of a glass slab normally, the refracted beam
goes straight through without bending
gets deviated away from the normal
gets bent towards the normal
gets reflected
The heating element often used in an electric iron is
copper
tungsten
mica
nichrome
Nichrome is used in electric heaters and irons because
it resists oxidation when red hot
its melting point is high
it has got 60 times the resistance of copper
All the above
Railway tracks are banked on curves so that
the necessary centrifugal force may be obtained from the horizontal component of the weight of the train
the frictional force between the track and the wheels is avoided
the necessary centripetal force may be derived from the horizontal component of the weight of the train
None of these
A solar eclipse occurs when the earth, the sun and the moon are in a straight line, and
when the moon passes between the sun and the earth
when the sun comes between the earth and the moon
when the earth comes between the sun and the moon
on a full moon day
A person cups his hand around the mouth when shouting. Why?
Sound energy from his mouth is then directed in one direction
The cupped hand acts as a cardboard tube of short length
The pitch of sound increases
Both (a) and (b)
An electric kettle used for boiling hard water has a white scale deposited on its heating element. This consists or
sugar
sodium carbonate
common salt
carbonates of calcium and magnesium
Heat is transmitted from one end of a metal rod to its other end by the method of
conduction
convection
radiation
sublimation
The inability of a body to change its state of rest or uniform motion along a straight line is called its
momentum
velocity
acceleration
inertia
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
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
Photocells are used
in burglar alarms
in automotive devices for light switches
television cameras
All the above
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 planet that moves fastest around the sun is
Mars
Venus
Earth
Mercury
A wire conveying a current deflects a pivoted magnetic needle. This was discovered by
Marconi
Oersted
Faraday
Ohm
While crossing a suspension bridge, the soldiers are ordered to break steps because
the marching in steps will involve a big strain on them
the resonant vibrations caused by their marching can damage the bridge increasing the amplitude to dangerous proportions
the marching may obstruct other traffic
rumblings of their marching may disturb the surroundings
A ship sailing from a river to the sea
sinks less in the sea
sinks more in the sea
neither sinks more nor less in the sea
sinking more or less depends on sea
A workman was working on a rail track. A young boy at a distance holds his ear close to the railway track. The boy was able to hear the sound of each blow or the workman twice. It is because
speed of sound is greater in steel than in air
speed of sound is greater in air than in steel
part of sound waves is reflected between rail tracks
the boy's ears are at a different distance from the source
In a longitudinal wave, the direction of propagation of the wave is
the same as the direction of the vibrations of the vibrating body
at right angles to the direction of the vibrations of the vibrating body
Both (a) and (b) above
None of the above
The focal length or lens or the eye is under the control or the
iris
pupil
ciliary body
cornea
Which is the densest planet of the solar system?
Sun
Jupiter
Mercury
Earth
The stars that shine brightly then dimly and then brightly are known as
meteors
binaries
variable stars
bright stars
A piece of cork la embedded inside an ice block which floats in water. What will happen to the level of water when all ice melts?
It will go down
It will come up
It will remain at the same level
First it will go down and it will come up
A radio set that uses valves does not start operating immediately when it is switched on whereas a set containing only tranaistors operates immediately. The reason for this is that
the valve filaments have low resistance
valve-radio sets work at a higher voltage
transistor set has a low resistance
filaments of the valves cake time to beat up and function
The largest reserve of radioactive element which can be used in a nuclear reactor has been found in India, The name of the element is
Thorium
Uranium
Plutonium
Radium