The ampere (symbol: A) is the SI base unit of electric current equal to one coulomb per second.
The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 times 10–7 newton per meter of length.
Electric current is the time rate of change or displacement of electric charge.
One ampere represents the rate of 1 coulomb of charge per second.
The ampere is defined first (it is a base unit, along with the meter, the second, and the kilogram), without reference to the quantity of charge.
The unit of charge, the coulomb, is defined to be the amount of charge displaced by a one ampere current in the time of one second.
This is your answer friend. Hope it helps you.
Answer:
Part a)

Part b)

Explanation:
Part a)
Electric potential is a scalar quantity
so here we can say that total potential due to a ring on its center is given as

here we know that



now we have


Part b)
Potential on the axis of the ring is given as



Answer:
Angular frequency is 20 rad/s.
Explanation:
Given that,
A block is attached to an oscillating spring. The function below shows its position (cm) vs. time (s) is given by :
.....(1)
The general equation of oscillating particle is given by :
.......(2)
Compare equation (1) and (2) we get :

So, the angular frequency of the oscillation is 20 rad/s.
It seems that you have missed the necessary options for us to answer this question so I had to look for it. Anyway, the answer to the given statement is FALSE. Pigments are NOT always made of natural materials. Pigments can either be man-made or the one that occurred naturally as what you see in our environment. Hope this helps.
If the object, ends up with a positive charge, then it is missing electrons. if it is missing electrons, then it must have been removed form the object during the rubbing process.