Electromagnetic Waves Test

Result

Electromagnetic Waves Test - 36

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following pairs of space and time varying
$$E(=\hat{i} E_x + \hat{j} E_y + \hat{k} E_z)$$ and $$B(=\hat{i}B_x + \hat{j}B_y + \hat{k} B_z)$$ would generate a plane electromagnetic wave travelling in the z-direction?

A
$$E_x, B_z$$

B
$$E_y, B_z$$

C
$$E_z, B_x$$

D
$$E_x, B_y$$

Solution
Question 2
1 / -0

A parallel plate capacitor of plate separation 2 mm is connected in an electric circuit having source voltage 400. What is the value of the displacement current for $$10^{-6}$$ s, if plate area is 60 $$cm^2$$?

A
1.062 x $$10^{-2}$$ A

B
2.062 x $$10^{-2}$$ A

C
3.062 x $$10^{-2}$$ A

D
5.062 x $$10^{-2}$$ A

Solution
Question 3
1 / -0

In an electromagnetic wave, the electric and magnetic fields are $$100 Vm ^{-1}$$ and $$0.265 Am$$ maximum energy flow is

A
$$26.5 W /m^{2}$$

B
$$36. 5 W / m^{2}$$

C
$$46.7 W / m^{2}$$

D
$$765 W / m^{2}$$

Solution

Given,
$$E_0=100V/m$$
$$B_0=0.265 A/m$$
Maximum rate of energy flow,
$$S=E_0\times B_0$$
$$S=100\times 0.265=26.5W/m^2$$
The correct option is A.
Question 4
1 / -0

A plane electromagnetic wave of angular frequency $$\omega $$ propagates in a poorly conducting medium
of conductivity $$\sigma $$ and relative permittivity $$\varepsilon $$. The ratio of maximum values of conduction current density and displacement current density in the medium is :

A
$$\dfrac {\varepsilon \varepsilon_0 \omega} \sigma $$

B
$$\dfrac \sigma {\varepsilon \varepsilon_0 \omega}$$

C
$$\dfrac {\omega} {\sigma \varepsilon _0 \varepsilon }$$

D
$$\dfrac {\omega \sigma } {\varepsilon _0 \varepsilon }$$

Solution
Question 5
1 / -0

For plane electromagnetic waves propagating in the positive Z direction, Which one of the following combination gives the correct possible direction of $$ \xrightarrow [ E ]{ } abd\xrightarrow [ B ]{ } $$ field respectively?

A
$$ \left( 2\hat { i } +3\hat { j } \right) and\left( \hat { i } +2\hat { j } \right) $$

B
$$ \left( -2\hat { i } -3\hat { j } \right) and\left( 3\hat { i } -2\hat { j } \right) $$

C
$$ \left( 3\hat { i } +3\hat { j } \right) and\left( 4\hat { i } -3\hat { j } \right) $$

D
$$ \left( \hat { i } +2\hat { j } \right) and\left(2 \hat { i } \hat { j } \right) $$

Solution
Question 6
1 / -0

If a plane electromagnetic wave satisfies the equation $$\dfrac{\partial ^2E_x}{\partial^2z}= C^2 \dfrac{\partial^2E_x}{\partial^2t},$$the wave propagates in

A
$$x$$-direction

B
$$z$$-direction

C
$$y$$-direction

D
$$xz$$ plane at an angle of $$45^0$$ between the $$x$$ and $$z$$direction
Question 7
1 / -0

What is the displacement current between the square plate of side 1 cm of a capacitor, if electric field between the, plates is changing at the rate of 3 x $$10^6 V_m^{-1}S^{-1}$$?

A
2.7 x $$10^{-9}$$ A

B
3.2 x $$10^{-9}$$ A

C
4.2 x $$10^{-9}$$ A

D
4.0 x $$10^{-9}$$ A

Solution
Question 8
1 / -0

An electromagnetic wave is radiated by a $$100W$$ bulb. If efficiency of the bulb is $$20$$% then the amplitude of magnetic field at a distance of $$1m$$ is (consider bulb as a point source)

A
$$\sqrt { \cfrac { 4 }{ 3 } } \times{10}^{-7}T$$

B
$$\sqrt { \cfrac { 1 }{ 3 } } \times{10}^{-7}T$$

C
$$2\times{10}^{-7}T$$

D
$$5\times{10}^{-7}T$$

Solution
Question 9
1 / -0

Choose the correct equation of maxwell ampere circuital law:

A
$$\oint \overline { B } \cdot \overline { d l } = \mu _ { 0 } \varepsilon _ { 0 } \frac { d \phi _ { E } } { d t }$$

B
$$\oint \overline { B } \cdot \overline { d l } = \mu _ { 9 } + \varepsilon _ { 0 } \frac { d \phi _ { E } } { d t }$$

C
$$\oint \vec { B } \cdot \overline { d l } = \mu _ { 0 } \left( i _ { c } + \varepsilon _ { 0 } \frac { d \phi _ { E } } { d t } \right)$$

D
$$\oint \overline { B } \cdot \overline { d l } = \mu _ { 0 } i _ { C } + \varepsilon _ { 0 } \frac { d \phi _ { \varepsilon } } { d t }$$

Solution
Question 10
1 / -0

A lamp emits monochoromatic green light uniformly in all directions. The lamp is $$3 \%$$ efficient in converting electrical power to electromagnetic waves and consumes $$100W$$ of power. The amplitude of the electric field associated with the electromagnetic radiation a distance of $$5\ m$$ from the lamp will nearly

A
$$1.34V/m$$

B
$$2.68V/m$$

C
$$4.02V/m$$

D
$$5.36V/m$$

Solution