A cup of hot coffee is placed on a metal table in a room. By which of the following methods does it lose heat?
conduction and convection only
conduction and radiation only
convection and radiation only
conduction, convection and radiation
Correct Answer :
D. conduction, convection and radiation
Related Questions
The coil of an electric heater is made of
Platinum
Tungsten
Nichrome
Copper
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
Which mirror is used as a rear view mirror in Vehicles?
Parabolic
Convex
Concave
Plain
The filament lamp is an example for
fluorescence
incandescence
both (a) and (b)
None of these
An ohm is a unit of
potential difference
resistance
current
All the above
Heat is transmitted from one end of a metal rod to its other end by the method of
conduction
convection
radiation
sublimation
In a microphone
sound energy is converted into electrical energy
electrical energy is converted into sound energy
sound energy is converted into mechanical energy
mechanical energy is converted into sound energy
A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because
the floor and carpet are at different temperatures
the stone conveys the heat away from the feet more rapidly than the carpet
the carpet is a better conductor of heat than the stone
the human body maintains a constant temperature
If a body weight 12N on the surface of the earth, how much will it weigh on the surface of the moon where acceleration due to gravity is only one-sixth of that on earth's surface?
12N
2N
10N
6N
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
Out of the following, name the fluorescent substance.
quinine sulphate solution
paraffin oil
fluorescein solutions
All the above
Which of the following is fissionable?
U-234
U-235
U-238
Both (b) and (c)
Echoes are produced by
the reflection of sound waves
the refraction of sound waves
the interference of sound waves
reverberation of sound waves
SONAR (Sound Navigation Ranging) is
used by warships and military aircraft to locate enemy submarines
used by ships to determine the depth of water beneath them
a detective device that uses sound to locate under - water objects
All the above
Which of the following can produce electricity?
resistor
thermocouple
light bulb
neon tube
Separating particles from a suspension is effected by
centrifugal force
frictional force
gravitational force
distillation
The power of a lens is
equal to its focal length
equal to its radius of curvature
equal to the reciprocal of its focal length (in metres)
equal to twice its focal length
The attraction of unlike molecules at the common surface is known as
adhesion
cohesion
surface tension
capillarity
The tiniest of the stars belong to the group known as
Giant stars
White Dwarf stars
Neutron stars
Super-giant stars
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
In the fuse of an electrical installation blows out
replace the fuse by a thin wire
replace the fuse by a thick copper wire
replace the fuse by a fuse wire of proper rating
replace the fuse by nichrome wire
Ultrasonic waves are used
in medical and surgical diagnosis
in testing the quality of the linings and pads used in vehicles and aircraft brakes
to clean surgical instruments, jewellery and similar articles
All the above
The filament used in the electric lamp is made of
nichrome
tungsten
copper
aluminium
In a refrigerator cooling is produced by
the ice that deposits on the freezer
the evaporation of a volatile liquid
None of the above
Both (a) and (b)
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
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 mode of travel of heat energy from the sun across the empty space beyond the earth's atmosphere is known as
conduction
convection
radiation
absorption
Photocells are used
in burglar alarms
in automotive devices for light switches
television cameras
All the above
Chronometer is an instrument to measure
heat
electric potential
time
distance between two points
What la 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