The force of attraction between 2 charged spheres can be explained by Coulomb's law,
It states the force of attraction is directly proportional to the magnitudes of the charges and inversely proportional to the square of the distance between the charges.
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where F - force of attraction/repulsion
q₁ and q₂ - charges of the 2 spheres
k - Coulomb's law constant
r - distance between the spheres
In the question given, the charges of the spheres remain constant in both instances, only distance changes. Therefore (kq₁q₂) = c which is a constant
then F = c / r²
first instance
6 x 10⁻⁹ N = c/ (20 cm)² ---1)
F = c/(10 cm)² --- 2)
2) / 1)

F = 6 x 10⁻⁹ x 4
F = 2.4 x 10⁻⁸ N
Answer: The correct answer is an emission line spectrum.
Explanation:
When the electrons are excited to the higher energy level, the energy is absorbed in this case.
When the electrons in the atom step down to lower energy levels in a thin cloud of hot gas then the radiation will emit.
The electron will lose energy in this case in the form of radiation. There will be an emission line spectrum.
Answer:
acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities. The orientation of an object's acceleration is given by the orientation of the net force acting on that object.
SI unit: m/s2, m·s−2, m s−2
B.---A. warm water B. thermocline C. cold water