Given :
The ball of a ballpoint pen is 0.5 mm in diameter and has an ASTM grain size of 12.
To Find :
How many grains are there in the ball?
Solution :
Volume of ball of the ballpoint is :
Now, grain size of 12 has about 520000 grains/mm³.
Therefore, number of grains are :
The magnitude of the electric field will be the greatest at the point where it is closest,to its charges.
Yes ,there is a point where the field will be zero.
what is an electric field?
The region where an electrostatic force is experienced by a charged entity is known as the electric field at a point.
As per the principle of field lines and vectors,where the field lines are in a close manner together,the field will be strongest.However ,where the field lines are in a manner apart,the field will be the weakest.
As per the concept,the electric field will be the greatest at the point where it is closest to its charges.For like charges, the electric field will be zero closer to the smaller charge and will be along the line joining the two charges. For opposite charges of equal magnitude, there will not be any zero electric fields.
Thus,we can conclude that there will be a point where the electric field is zero
learn more about electric field from here: brainly.com/question/28197462
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Answer:
The kinetic energy K of the moving charge is K = 2kQ²/3d = 2Q²/(4πε)3d = Q²/6πεd
Explanation:
The potential energy due to two charges q₁ and q₂ at a distance d from each other is given by U = kq₁q₂/r.
Now, for the two charges q₁ = q₂ = Q separated by a distance d, the initial potential energy is U₁ = kQ²/d. The initial kinetic energy of the system K₁ = 0 since there is no motion of the charges initially. When the moving charge is at a distance of r = 3d, the potential energy of the system is U₂ = kQ²/3d and the kinetic energy is K₂.
From the law of conservation of energy, U₁ + K₁ = U₂ + K₂
So, kQ²/d + 0 = kQ²/3d + K
K₂ = kQ²/d - kQ²/3d = 2kQ²/3d
So, the kinetic energy K₂ of the moving charge is K₂ = 2kQ²/3d = 2Q²/(4πε)3d = Q²/6πεd
