Electromagnetic Waves Test

Result

Electromagnetic Waves Test - 19

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

In the propagation of electromagnetic waves the angle between the direction of propagation and the plane of vibration is ________

A
$$\pi$$

B
$$\displaystyle\frac{\pi}{2}$$

C
$$\displaystyle \frac{\pi}{4}$$

D
$$0$$

Solution

Axis of propagation always lie perpendicular to the plane of vibrations, therefor angle between them is $$\dfrac{\pi}{2}$$ .
Hence answer is B
Question 2
1 / -0

When light propagates in vaccum there is an electric field and a magnetic field. Which of the following is not true about these field?

A
They are constant in time

B
They have zero average value

C
They are perpendicular to the direction of propagation of light

D
They are mutually perpendicular

Solution

$$Answer:-$$ A
They vary with time following a wave function (sinuosoidal) and average value of these function is zero and also we can see in figure they are mutually perpendicular and also perpendicular to direction of propagation.
Question 3
1 / -0

The value of electric field in an electromagnetic wave originating from a point source of light at a distance of 10 meter is E= 500 volt/m. The electric field at a distance of 5 meter will be

A
1000 Volt/meter

B
2000 Volt/meter

C
50 Volt/meter

D
25 Volt/meter

Solution

As we know, $$ E \propto R^{-2} $$
Therefore , $$ E( R= 5) = \dfrac{500}{10^{-2}} 5^{-2} = 2000 V/m $$
Question 4
1 / -0

Maxwell's modified form of Ampere's circuital law is

A
$$\displaystyle\oint_{\displaystyle s}{\vec{B}.\vec{ds}}=0$$

B
$$\displaystyle\oint_{\displaystyle s}{\vec{B}.\vec{dl}}=\mu_0I$$

C
$$\displaystyle\oint_{\displaystyle s}{\vec{B}.\vec{dl}}=\mu_0I+\frac{I}{\varepsilon_o}\frac{dq}{dt}$$

D
$$\displaystyle\oint_{\displaystyle s}{\vec{B}.\vec{dl}}=\mu_0I+\mu_0\varepsilon_o\frac{d\phi_E}{dt}$$

Solution

$$Answer:-$$ D
Treating all charges on the same footing (disregarding whether they are bound or free charges), the generalized Ampère's equation, also called the Maxwell–Ampère equation, is in integral form.
Question 5
1 / -0

Assume you are sitting in sun for 2.5 hours. The area of your body exposed normally to sun rays $$ { 1.3m }^{ 2 }$$. The intensity of sun rays is 1.1 Kilowatt/$${ m }^{ 2 }$$. If your body completely absorbs the sun rays then the momentum transferred to your body will be (in Kg-m/s):

A
$$0.043$$

B
$$0.037$$

C
$$0.61$$

D
$$-0.91$$

Solution

$$Power=intensity\times area$$
Intensity and area are given ,
$$Power=1.3\times 1.1KW$$
$$Energy = power\times time$$
Time is 2.5hr
$$Energy= 1300\times 1.1\times 2.5\times 3600J$$
$$=12870000J$$
$$Momentum=\dfrac{energy}{c}$$
$$=\dfrac{12870000}{3\times 10^{8}}$$
$$=0.043$$
Question 6
1 / -0

The displacement current is

A
$$\displaystyle\varepsilon_o\frac{d\phi_E}{dt}$$

B
$$\displaystyle\frac{\varepsilon_o}{R}\frac{d\phi_E}{dt}$$

C
$$\displaystyle\varepsilon_o\frac{E}{R}$$

D
$$\displaystyle\varepsilon_oq\frac{C}{R}$$

Solution
Question 7
1 / -0

In the propagation of light waves, the angle between the plane of vibration & plane of polarisation is:

A
0$$^0$$

B
90$$^0$$

C
45$$^0$$

D
80$$^0$$

Solution

The plane of polarisations is that plane in which there is no vibration. While a plane including the direction of light propagation and the direction of electric field is called the plane of vibration. The angle between them is $$ { 90 }^{ o }$$.
Question 8
1 / -0

In the propagation of electromagnetic waves, the angle between the direction of propagation and plane of polarisation is

A
0$$^0$$

B
45$$^0$$

C
90$$^0$$

D
180$$^0$$

Solution

Plane of polarization is a confinement of the electric/magnetic field vector to a given plane along the direction of propagation. Therefore angle between them is $$ { 0 }^{ o }$$
Question 9
1 / -0

If $$\vec{E}$$ and $$\vec{B}$$ are the electric and magnetic field vectors of electromagnetic waves then the direction of propagation of electromagnetic wave is along the direction of:

A
$$\vec{E}$$

B
$$\vec{B}$$

C
$$\vec{E}\times\vec{B}$$

D
None of the above

Solution

The direction of propagation of electromagnetic wave is perpendicular to the variation of electric field $$\vec{E}$$ as well as to the magnetic field $$\vec{B}$$
Question 10
1 / -0

Which of the following has/have zero average value in a plane electromagnetic wave?

A
Both magnetic and electric field

B
Electric field only

C
Magnetic energy

D
Electric energy

Solution