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# Test: Maxwell Law in Time Varying Fields

## 10 Questions MCQ Test Electromagnetic Fields Theory | Test: Maxwell Law in Time Varying Fields

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

### Find the curl of E when B is given as 15t.

Solution:

Explanation: From Maxwell first law, we get Curl of E as the negative derivative of B with respect to time. Thus Curl(E) = -dB/dt. On substituting B= 15t and differentiating, Curl(E) = -15 units.

QUESTION: 2

### The charge build up in a capacitor is due to

Solution:

Explanation: The capacitor consists of a dielectric placed between two conducting plates, subjected to a field. The current due to a dielectric is always due to the displacement current density.

QUESTION: 3

### The surface integral of which parameter is zero?

Solution:

Explanation: The divergence of the magnetic flux density is always zero. By Stokes theorem, the surface integral of B is same as the volume integral of the divergence of B. Thus the surface integral of B is also zero.

QUESTION: 4

Harmonic electromagnetic fields refer to fields varying sinusoidally with respect to time. State True/False.

Solution:

Explanation: Fields that varying sinusoidally with respect to time are called as harmonic fields. An example for harmonic fields is A sin wt.

QUESTION: 5

When electric potential is null, then the electric field intensity will be

Solution:

Explanation: The electric field intensity is given by E = -Grad(V)- dA/dt, where V is the electric potential and A is the magnetic vector potential. When V is zero, then E = -dA/dt.

QUESTION: 6

The gradient of the magnetic vector potential can be expressed as

Solution:

Explanation: The gradient of A is the ratio of the negative gradient of electric potential to the speed of light c. We can write c = 1/√(με). Thus grad(A) = -με dV/dt is the required expression.

QUESTION: 7

Find the time constant of a capacitor with capacitance of 2 microfarad having an internal resistance of 4 megaohm.

Solution:

Explanation: The time constant of capacitor is given by T = RC, where R = 4×106 and C = 2×10-6. Thus T = 4×106 x2x10-6 = 8 seconds.

QUESTION: 8

Which components exist in an electromagnetic wave?

Solution:

Explanation: In an electromagnetic wave, the electric and magnetic components coexist. They propagate perpendicular to each other and to the direction of propagation in space.

QUESTION: 9

The propagation of the electromagnetic waves can be illustrated by

Solution:

Explanation: By Flemming’s rule, when the thumb and the middle finger represent the inputs (say current and field respectively), then the fore finger represents the output (force, in this case). The EM propagation can be illustrated by this rule.

QUESTION: 10

Which one of the following laws will not contribute to the Maxwell’s equations?

Solution: