9.
2 answers:
Answer:
Newton is the unit of the force in standard metric.
Option: C
<u>Explanation: </u>
The physical quantity which has both direction and magnitude is force. Force is also known as to be a pull or push of an object with respect to its mass that is responsible for the change in velocity (acceleration). To give motion for an object from one place to another force is to be applied on an object.
So, Force= mass x acceleration = kg x = Newton (N)
Symbolically Newton is represented as N.
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1-2) They have same surface charge density
3-4) The metallic conductor has greatest surface charge density
Explanation:
1-2)
In a conductor, the charge carriers (mainly electrons) are free to move. Therefore, as a result, they tend to move at the largest possible distance from each other, because of the repulsive force that they exert on each other.
The configuration that maximize the distance between the charge carriers for a solid sphere of metallic conductor is the one in which all the electrons are on the surface, and they are equally spaced between each other. This means that for the solid sphere of radius R, the excess charge Q will be entirely spread over the surface of the sphere.
Similarly, the excess charge Q on the hollow spherical shell (which is also made of the same conducting material) will also be spread over the surface with the charge carriers at the maximum distance from each other. Therefore, the surface charge density for both objects will be
where R is the radius of the two spheres.
3-4)
In this case, the surface charge density on the two objects is different.
In fact, on the metallic sphere (conducting) the surface charge density is (as explained in part 1):
Hoever, the second sphere is made of an insulating material. In an insulator, the charge carriers are not free to move. If the initial charge Q is spread across the all sphere (which is not hollow), this means that some of the charge will actually also be inside the sphere. So the charge deposited on the surface, Q', will be less than the total charge Q. Therefore, the surface charge density will be
And since Q' < Q, this means that , so the conducting sphere has a greatest surface charge density.