Solved Examples on Electric Charges

Example 1: How many electrons are present in 1 Coulomb of charge?

Solution:

In a single electron, charge is equal to 1.6 × 10^-19C

1.6× 10^-19C = 1 electron

1C = 1/(1.6 × 10^-19) electrons

1C = 6.25 × 10¹⁸ electrons

Example 2: How many Protons are present in 10 C of charge?

Solution:

According to the Quantization of charge,

Q = ne

Q = 10 C
n = number of protons
e = 1.6 × 10^-19C

10 = n × 1.6× 10^-19

n = 625 × 10¹⁷ protons

Example 3: In a system, the charges present are +5C, -7C, +1C, +9C, -15C. What is the total charge on the system?

Solution:

According to the Additivity property of Electric charges,

Q = q₁+ q₂+ q₃+ q₄+ q₅

Q = +5C + (-7C) + 1C+ 9C+ (-15C)

Q = -7C

Example 4: Two charges +5C and +3C are placed at 1 meter apart in Free Space. Find the Force acting on them, and state the type of force as well.

Solution:

Force acting on +5C and +3C in free space is given by,

[Tex]F= \frac{1}{4\pi\epsilon_o}\frac{q_1q_2}{r^2}\\ F= 9\times10^9\frac{(5\times3)}{1^2}\\ F= 135\times10^9\\ F= 1.35\times10^{11}N [/Tex]

Since, the charge +5C and +3C are alike in nature, i.e. they are both positive, hence, the force acting between them is the Repulsive Force.

Electric charge is the fundamental property of matter. Various properties are explained by the electric charges. So it is very important to note the unit of electric charge and other parameters of the electric charge. In this article, we will learn about electric charge its definition, and the units of electric charge in detail.