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# Test: Electric Dipole

## 10 Questions MCQ Test Electromagnetic Theory | Test: Electric Dipole

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

### Choose the best definition of a dipole.

Solution:

Explanation: An electric dipole generally refers to two equal and unlike (opposite signs) charges separated by a small distance. It can be anywhere, not necessarily at origin.

QUESTION: 2

### The potential due to a dipole at a point P from it is the

Solution:

Explanation: The total potential at the point P due to the dipole is given by the difference of the potentials of the individual charges.
V = V1 + (-V2), since both the charges are unlike. Thus V = V1 – V2.

QUESTION: 3

### Calculate the dipole moment of a dipole with equal charges 2C and -2C separated by a distance of 2cm.

Solution:

Explanation: The dipole moment of charge 2C and distance 2cm will be,
M = Q x d. Thus, M = 2 x 0.02 = 0.04 C-m.

QUESTION: 4

Find the angle at which the potential due a dipole is measured, when the distance from one charge is 12cm and that due to other is 11cm, separated to each other by a distance of 2cm.

Solution:

Explanation: Here, the two charges are separated by d = 2cm.
The distance from one charge (say Q1) will be R1 = 11cm. The distance from another charge (say Q2) will be R2 = 12cm. If R1 and R2 is assumed to be parallel, then R2 – R1 = d cos θ. We get 1 = 2cos θ and cos θ = 0.5. Then θ =
cos-1(0.5) = 60.

QUESTION: 5

Find the potential due the dipole when the angle subtended by the two charges at the point P is perpendicular.

Solution:

Explanation: The potential due the dipole is given by, V = m cos θ/(4πεr2). When the angle becomes perpendicular (θ = 90). The potential becomes zero since cos 90 will become zero.

QUESTION: 6

For two charges 3C and -3C separated by 1cm and are located at distances 5cm and 7cm respectively from the point P, then the distance between their midpoint and the point P will be

Solution:

Explanation: For a distant point P, the R1 and R2 will approximately be equal.
R1 = R2 = r, where r is the distance between P and the midpoint of the two charges. Thus they are in geometric progression, R1R2=r2
Now, r2 = 5 x 7 = 35. We get r = 5.91cm.

QUESTION: 7

Calculate the distance between two charges of 4C forming a dipole, with a dipole moment of 6 units.

Solution:

Explanation: The dipole moment is given by, M = Q x d. To get d, we rearrange the formula d = M/Q = 6/4 = 1.5units.

QUESTION: 8

The potential due to the dipole on the midpoint of the two charges will be

Solution:

Explanation: The potential due a dipole at a point P will be V = m cos θ/(4πεr2).
Now it is given that potential on the midpoint, which means P is on midpoint, then the distance from midpoint and P will be zero. When r = 0 is put in the above equation, we get V = ∞. This shows that the potential of a dipole at its midpoint will be maximum/infinity.

QUESTION: 9

Dipoles in any electric field undergo

Solution: