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
Correct Answer :
A. the electrical attraction between the negatively charged electron and the positively charged porton
Related Questions
The loudness of a sound is determined by
Frequency
Amplitude
Speed
Wavelength
Dioptre is the unit of power of
convex mirrors
concave mirrors
concave lenses
lenses irrespective of types
Lightning conductors are made of
iron
chromium
copper
steel
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
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
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
The unit of power in SI is
Joule
Newton
Joule/Sec
Erg/Sec
Who first established the fact that the earth revolves round the sun?
Sir Isaac Newton
Kepler
Copernicus
Ptolemy
The force that keeps a body in a circular motion la called
the centripetal force
the centrifugal force
the frictional force
All the above
Choose the correct answer
Microphone converts sound energy into electrical energy.
Electric fan converts electrical energy into mechanical energy.
Battery converts chemical energy into electrical energy.
All the above
In experiments on static electricity the standard method for obtaining small amounts of positive electricity is to rub
a glass rod with flannel
an abonite rod with flannel
a glass rod with silk
Any of the above
The mass number and the atomic number of an element are X and Y respectively. The number oC neutrons in the atom of that element is
X
Y
X + Y
X Y
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
In an oil lamp, holes are provided below the chimney so that
necessary oxygen for burning of oil may be provided
the convection current of air may be maintained to keep the lamp burning
the brightness of the lamp may be increased
All the above
A thermostat is a device used
for automatically maintaining a steady temperature
for measuring electricity
to reduce the voltage of electricity
for producing heat
The coil of an electric heater is made of
Platinum
Tungsten
Nichrome
Copper
A piece of ice is Boating In water kept in a beaker. When all the ice melts the level of water will
first rise and then fall
fall
remain the same
rise
Sound waves
are electromagnetic waves
can easily pass through vacuum
are always transverse waves
require a material medium for propagation
Who discovered that the Cree Call acceleration Is the same for any object at a given place?
Newton
Pascal
Archimedes
Galileo
The aneroid barometer uses
mercury
distilled water
alcohol
does not use any liquid
The phenomenon of radioactivity was discovered by
Rutherford
Bohr
Henri Bacquerel
Marie Curie
Credit for starting Space Science Research in India goes to
HJ Bhabha
SS Bhatnagar
V Sarabhai
CV Raman
The leader of the team who succeeded in constructing the first nuclear reactor (an atomic pile) in the world was
Albert Einstein
Enrico Fermi
HJ Bhabha
Sir Isaac Newton
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
Halley's comet appears in the heavens once in
40 years
50 years
76 years
80 years
The fact that two large ships travelling on close parallel courses in the same direction tend to move towards each other can be explained by
Bernoulli's principle
Magnetic properties of the ship's material
Newton's third law of motion
Earth's gravitational force
Mercury is used in thermometers because
it has high thermal conductivity
it has uniform expansivity
it has high boiling point and low freezing point
of all the above
The plants in a greenhouse are enclosed in a glass enclosure because
glass allows the heat radiations of shorter wavelengths from the sun to pass through
the plants absorb them - these shorter wavelengths - and reradiate them in the form of longer wavelengths
the longer wavelengths cannot penetrate through the glass walls
All the above
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
The instrument used to measure the strength of electric current at a point is
Ammeter
Altimeter
Adrinometer
Anemometer