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# Test: Coulomb Law

## 10 Questions MCQ Test Electromagnetic Fields Theory | Test: Coulomb Law

Description
This mock test of Test: Coulomb Law for Electronics and Communication Engineering (ECE) helps you for every Electronics and Communication Engineering (ECE) entrance exam. This contains 10 Multiple Choice Questions for Electronics and Communication Engineering (ECE) Test: Coulomb Law (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Coulomb Law quiz give you a good mix of easy questions and tough questions. Electronics and Communication Engineering (ECE) students definitely take this Test: Coulomb Law exercise for a better result in the exam. You can find other Test: Coulomb Law extra questions, long questions & short questions for Electronics and Communication Engineering (ECE) on EduRev as well by searching above.
QUESTION: 1

### Coulomb is the unit of which quantity?

Solution:

Explanation: The standard unit of charge is Coulomb. One coulomb is defined as the 1 Newton of force applied on 1 unit of electric field

QUESTION: 2

### Coulomb law is employed in

Solution:

Explanation: Coulomb law is applied to static charges. It states that force between any two point charges is proportional to the product of the charges and inversely proportional to square of the distance between them. Thus it is employed in electrostatics.

QUESTION: 3

### Find the force between 2C and -1C separated by a distance 1m in air(in newton).

Solution:

Explanation: F = q1q2/(4∏εor2) = -2 X 9/(10-9 X 12) = -18 X 109.

QUESTION: 4

Two charges 1C and -4C exists in air. What is the direction of force?

Solution:

Explanation: Since the charges are unlike, the force will be attractive. Thus the force directs from 1C to -4C.

QUESTION: 5

Find the force of interaction between 60 stat coulomb and 37.5 stat coulomb spaced 7.5cm apart in transformer oil(εr=2.2) in 10-4 N,

Solution:

Explanation: 1 stat coulomb = 1/(3 X 109) C
F = (1.998 X 1.2488 X 10-16)/(4∏ X 8.854 X 10-12 X 2.2 X (7.5 X 10-2)2) = 1.815 X 10-4 N.

QUESTION: 6

Find the force between two charges when they are brought in contact and separated by 4cm apart, charges are 2nC and -1nC, in μN.

Solution:

Explanation: Before the charges are brought into contact, F = 11.234 μN.
After charges are brought into contact and then separated, charge on each sphere is, (q1 + q2)/2 = 0.5nC
On calculating the force with q1 = q2 = 0.5nC, F = 1.404μN.

QUESTION: 7

The Coulomb law is an implication of which law?

Solution:

Explanation: The Coulomb law can be formulated from the Gauss law, using the divergence theorem. Thus it is an implication of Gauss law.

QUESTION: 8

Two small diameter 10gm dielectric balls can slide freely on a vertical channel. Each carry a negative charge of 1μC. Find the separation between the balls if the lower ball is restrained from moving.

Solution:

Explanation: F = mg = 10 X 10-3 X 9.81 = 9.81 X 10-2 N.
On calculating r by substituting charges, we get r = 0.3m.

QUESTION: 9

A charge of 2 X 10-7 C is acted upon by a force of 0.1N. Determine the distance to the other charge of 4.5 X 10-7 C, both the charges are in vacuum.

Solution:

Explanation: F = q1q2/(4∏εor2) , substituting q1, q2 and F, r2 = q1q2/(4∏εoF) =
We get r = 0.09m.

QUESTION: 10

For a charge Q1, the effect of charge Q2 on Q1 will be,

Solution: