The function of a moderator in a nuclear reactor is
to absorb unwanted neutrons
to slow down the fast neutrons to secure more effective hits on other nuclei
to decrease the number of fissile nuclei
to increase the number of fissile nuclei
Correct Answer :
B. to slow down the fast neutrons to secure more effective hits on other nuclei
Related Questions
The method used to separate aluminium from a alumina is
electroplating
electrotyping
electrolysis
distillation
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
Light from the sun reaches the earth in
2 minutes
4 minutes
12 minutes
8 minutes
The hygrometer is an apparatus used for finding the
temperature of air
intensity of light
density of a liquid
relative humidity of the atmosphere
Increase in pressure
increases the melting point of ice
decreases the melting point of ice
has no effect on the melting point of ice
increases the volume of the ice
A tube light works on the principle of
chemical, heating and magnetic effects of electricity
discharge of electricity through gases
the action of ultraviolet radiation on certain fluorescent materials
Both (b) and (c) above
For accurate scientific work, temperatures are often measured by
mercury thermometers
alcohol thermometers
platinum resistance thermometers
thermoelectric thermometers
The cover of a solar cooker is made of glass because
it absorbs sun's rays
it reflects sun's rays
it retains the heat inside by the greenhouse effect
it radiates heat better than metals
Of the following which has got the highest frequency?
ultraviolet rays
gamma rays
radio waves
infrared waves
Which of the following wires of same dimensions offers least resistance to the ,flow of current?
copper
aluminium
silver
nichrome
The speed of sound in air at 0° C is approximately
4 x 108 m/s
1500 m/s
330 m/s
500 m/s
The sun continuously produces an enormous amount of energy. This la due to
nuclear fission
nuclear fusion
chemical combustion
boiling
In a freezer ice cubes will be formed more quickly in trays made of
rubber
plastic
aluminium
wood
Meteors
look like falling stars
are really pieces of rock or metal
burn up as they shoot through the air
All the above
A transformer
converts direct current into alternating current
converts alternating current into direct current
steps up or steps down a given alternating current voltage
supplies current with zero resistance
The phenomenon of spontaneous disintegration of certain heavy nuclei is termed
radioactivity
fission
fusion
implosion
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
A cyclist leans inwards when he is negotiating a curve 10 that
he may increase his speed
his weight may be reduced
necessary centripetal force may be available from the horizontal component of the normal reaction due to the track to maintain the curved motion
no frictional force may be produced between the wheels and the axle
The function of a ruse wire is
to stabilise the voltage
to decrease the current supply
to increase the current supply
to prevent an unduly high current from passing through a circuit
A proton is
the ionised hydrogen molecule
the nucleus of helium atom
the nucleus of hydrogen atom
the positive counterpart of electron
You want a supply of a small but constant current. Which of the following cells will you prefer?
Daniell cell
Leclanche cell
Dry cell
All the above
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
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
Alpha particles are
electromagnetic radiations
helium nuclei
negatively charged particles
neutral particles
How is it that Pluto is not always the farthest planet of the solar system?
Each planet becomes the farthest planet in its turn. Now it is the turn of Piuto
The Sun is now in the zodiac in which it is nearest to outer planets
The eccentricity of Piuto's orbit being substantial, this orbit cuts the orbit of Neptune
Piuto belongs to other solar system
The ozone layer absorbs
Cosmic rays
Infrared rays
All radiations of light
Ultra violet rays coming from the sun
Formation of shadows can be explained by
rectilinear propagation of light
reflection
refraction
total internal reflection
Among the following the most suitable material for the core of an electro-magnet is
steel
wood
soft iron
copper
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
The cell that can be recharged, after it has run down, by passing a direct current through it from a source of current is
Voltaic cell
Leclanche cell
Dry cell
An accumulator