ELECTRICAL FORCE

The force exerted by two charged objects to each other. Calculation of the force that the same or oppositely charged objects applies to each other. The subject expression and examples.


The Electrical Charge

There are two types of electrical charge in the natura. These are the positively charge and the negatively charge.

The charge type of any object can understandable looking to the ratio of electron/proton. 

If the ratio of electron/proton is bigger than 1, the object has been charged by negatively (-) charge.

If the ratio of electron/proton is smaller than 1, the object has been charged by positively (+) charge.

If the ratio of electron/proton is equal to 1, the object is neutral. That is, the object has been not charged by positively or negatively charged.

The electric charge in solids depends on the number of electrons, the electric charge in the solutions depends on the number of the ions.


The protons and electrons are in interaction with each other. The protons are attracts the electrons to the itself. The electrons are attracts the protons to the itself.

The protons are repels the protons, the electrons are repels the electrons.

This interaction between the electrons and protons is called the electrical force.

These forces are equal to each other and direction of these forces are opposite to each other.

The electrical force that two objects with charge of q1 and q2 applies to each other is found as the following.

F = k* q1 * q2
r2




The force applied by two objects to the each other is magnitude of equal, and its directions are opposite to the each other.

F = Electrical force

q1= Electrical charge

q2 = Electrical charge

r = distance

k = Coulomb’s constant

k ≅ 9.109 N.m2
C2




k ≅ 1
4π.ɛ0




ɛ0   : is the permittivity

ɛ0 ≅ 8.85.10-12 C2
N.m2




The unit of electric charge is Coulomb (C).

The charge of one proton or electron is 1.6x10-19 C

6.242x1018 electron is equal to 1 C

1 C = 6.242x1018 e

The charge of one proton or one electron is called the elementary charge.

The magnitude of this force applied is directly proportional to multiplying of the charges, and is inversely proportional to distance between the charges.

The electric charges with same sign repel each other.


Electrical_T1q1


In the following figure, the q1 and q2 electric charges repel each other.


Electrical_T1q3


The electric charges with opposite sign attract each other.

In the following figure, The charge q2 attract to the charge q1 to itself. Also, The charge q1 attract to the charge q2 to itself too. 

Electrical_T1q2


Example:

Electrical_T1q4


The distance between the electric charges which in the figure above is 6 meters.

Charge of the q1 is (-3)*10-3 C, and charge of the q2 is (-5)*10-4 C.

Find the repel force that electric charges apply each other.

 (k= 9.109.N.m2/C2)


Solution:

Suppose that the repel force that the q1 charge is apply to the q2 is F1, and repel force that the q2 apply to the q1 is F2.

F1 = k*q1*q2
r2




F1 = 9*109 *(-3)* 10-3 * (-5)*10-4
36




F1 = 9*(-3)*(-5)*10(9 – 3 – 4)
36




F1 = 135*102
36




F1 = 3.75*100

F1 = 375 N


The force F2 is equal to the force F1, and direction of the force F2 is opposite to the direction of the force F1.


F2 = -375 N

Example:

Electrical_T1q5

Two electric charge is seen in the figure above. The q1 charge is (-0.12 ) C, and the q2  charge is (+0.18) C. The distance between two charge is 5 m.

The attract force applied by electric charges to each other how many Newtons?


 (k = 9.109 N.m2/C2)


Solution:

F = kq1*q2
r2



F = 9.10(-0.12)*(0.18)
25




F = 7.776*106 N

F = 7.776 Mega Newton


Example:

Electrical_T1q6


Two electric charges are seen in the figure above. The charge q1 is 12*10-5 C, and the charge q2 is 6*10-4 C.

The electrical force applied by charge q1 to the q2 charge is 8 Newton.

How many meters is the distance between two electric charge?

(k = 9.109 N.m2/C2)


Solution:

The magnitudes of the forces that the charges q1 and q2 apply to each other is equal, and its directions are opposite.

F(1,2) = 8 N,

F(1,2) = 9*10912*10-5 * 6*10-4
x2




8 = 9*12*6*10(9-9)
x2




8x2  = 648

x2 = 81

x = 9 m


Electrical Force Questions


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December 25 2018

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