The net charge on the atom is zero because
the electrons and the protons that are charged are in the nucleus
the total charge on the electrons is equal to the total charge on the protons
the neutrons from a shield around the charged protons
the number of electrons in an atom is half the number of protons
A and B above
Correct answer is B
An atom is defined as having the same number of electrons (negative charge), protons (positive charge) and neutrons (no charge). This means that it will have the same amount of negative and positive charge, giving it a net zero charge. On the other hand, an ion has different amount of electrons and protons.
Of the following, which is different from the others?
x-rays
gamma-rays
cathode rays
ultra violet rays
infrared rays
Correct answer is C
No explanation has been provided for this answer.
For the correction of myopic defects in the human eye we require
a convex lens
a concave lens
a combination of concave and convex lenses
a prism
a concave mirror
Correct answer is B
No explanation has been provided for this answer.
A string is sustaining a stationary wave when
the frequency of the wave is not proportional to the wavelength of the wave
the amplitude of vibration is always zero
two equal waves are travelling in opposite directions
the waves are longitudinal
the frequency is directly proportional to the length of the string
Correct answer is C
-Standing waves are produced on a string when equal waves travel in opposite directions.
-A stretched string is fixed at both ends, when it is plucked at mid point, two reflected waves of same amplitude and frequency at the ends are travelling in opposite direction and overlap along the length. Then the resultant waves are known as the standing waves (or) stationary waves.
The angular dispersion of a prism depends on
the index of refraction only
the angle of incidence as well as the index of refraction
the angle of incidence only
the thickness of the prism
the prism angle
Correct answer is A
No explanation has been provided for this answer.