Physics - Electromagnetic Waves - Quiz-2

On an EM wave, the amplitude of electric and magnetic fields are 100 v/m and 0.265 A/m. The maximum energy flow is

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26.5 $W / m^{2}$
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46.7 $W / m^{2}$
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66.5 $W / m^{2}$
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86.5 $W / m^{2}$

The most penetrating radiation out of the following is:

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X-rays
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$β$ -rays
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$α$ -rays
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$γ$ -rays

Which of the following statements about electromagnetic waves is/are correct:

A. X-rays in vacuum travel faster than light waves in vacuum.

B. The energy of an X-ray photon is greater than that of a light photon.

C. Light can be polarised but X-ray cannot.

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A and B
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B and C
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A, B and C
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B only

The magnetic field in a plane EM wave traveling in the positive x-direction is given by

$B = (100 μT) \sin [(2 \times 10^{15} s^{- 1}) (t - x / c)] \hat{j}$

The equation for electric field is :

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E=100sin [(2 $\times 10^{15} s^{- 1})$ (t-x/c)] $(- \hat{k})$
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E=(3 $\times 10^{10} μ V / m$ )sin [(2 $\times 10^{15} s^{- 1})$ (t-x/c)] $(- \hat{k})$
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E=3 $\times 10^{10}$ sin [(2 $\times 10^{15} s^{- 1})$ (t-x/c)] $\hat{k}$
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E=100sin [(2 $\times 10^{15} s^{- 1})$ (t-x/c)] $\hat{k}$

Statement I: A changing electric field produces a magnetic field.

Statement II: A changing magnetic field produces an electric field.

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If both statement-I and Statement-II are true, and Statement-II is the correct explanation of Statement-I.
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If both Statement-I and Statement-II are true but Statement-II is not the correct explanation of Statement-I.
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If Statement-I is true but Statement-II is false.
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If Statement-I is false but Statement-II is true.
1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

Statement-I: Gamma rays are more energetic than X-rays.

Statement-II: Gamma rays are of nuclear origin but X-rays are produced due to sudden deceleration of high energy electrons while falling on a metal of high atomic number.

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If both statement-I and Statement-II are true, and Statement-II is the correct explanation of Statement-I.
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If both Statement-I and Statement-II are true but Statement-II is not the correct explanation of Statement-I.
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If Statement-I is true but Statement-II is false.
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If Statement-I is false but Statement-II is true.
1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

The S.I unit of displacement current is

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Henry
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Coulomb
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Ampere
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Farad

The relation between electric field E and magnetic field intensity H in an electromagnetic wave is:

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E = H
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$E = \frac{μ_{0}}{ε_{0}} H$
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$E = \sqrt{\frac{ε_{0}}{μ_{0}}} H$
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$E = \sqrt{\frac{μ_{0}}{ε_{0}}} H$

An electromagnetic wave going through Vaccum is described by

$E = E_{0} \sin (k x - ω t) B = B_{0} \sin (k x - ω t)$

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$E_{0} B_{0} = ω k$
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$E_{0} ω = B_{0} k$
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$E_{0} k = B_{0} ω$
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none of these

The shortest wavelength of X-rays emitted from an X-ray tube depends upon

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nature of the gas in the tube
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the voltage applied to the tube
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current in the tube
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nature of the target of the tube

The ratio of $\frac{E_{0}}{H_{0}}$ for a plane electromagnetic wave has the dimension of

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Impedance
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Resistance
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Both
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None

An electromagnetic wave going through a medium is given by $E = E_{0} \sin (kx - ωt)$ and $B = B_{0} \sin (kx - ωt)$ then

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$E_{0} k = B_{0} ω$
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If Electric field is in Z direction them magnetic field should be in - y direction
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Both 'A' and 'B' are correct
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Only A is correct

A plane E M wave of frequency 25 MHz travels in free space in the x-direction. At a particular point in space and time $E = 6.3 \hat{j} V / m$ then B at the point is

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$2.1 \times 10^{- 8} - \hat{k}$
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$2.1 \times 10^{- 8} \hat{k}$
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2.1 $\hat{k}$
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$2.1 \times 10^{- 8} \hat{i}$

In an electromagnetic wave, the amplitude of electric field is 1 V/m. The frequency of wave is $5 \times 10^{14} H z$ . The wave is propagating along Z-axis. The average energy density of electric field in joule/ $m^{3}$ , will be

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$2.2 \times 10^{- 12}$
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4.4 $\times 10^{- 12}$
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6.6 $\times 10^{- 12}$
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8.8 $\times 10^{- 12}$

The infra-red spectrum lies between :

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radio wave and microwave region
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the micro-wave and visible region
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the visible and ultraviolet region
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the ultraviolet and the X-ray region

Consider an electric charge oscillating with a frequency of 10 MHz. The radiation emitted will have a wavelength equal to

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20 m
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30 m
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40 m
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10 m

Which of the following electromagnetic waves has minimum frequency?

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Radio waves
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Infrared waves
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Microwaves
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X-rays

A parallel plate capacitor consists of two circular plates each of radius 12 cm and separated by 5.0 mm. The capacitor is being charged by an external source. The charging current is constant and is equal to 0.15 A. The rate of change of the potential difference between the plates will be :

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$1.873 \times 10^{7} V / s$
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$1.873 \times 10^{8} V / s$
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$1.873 \times 10^{9} V / s$
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$1.873 \times 10^{10} V / s$

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

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1.34 V/m
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2.68 V/m
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4.02 V/m
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5.36 V/m

A parallel plate capacitor consists of two circular plates each of radius 2 cm, separated by a distance of 0.1 mm. If the voltage across the plates is varying at the rate of $5 \times 10^{13}$ V/s, then the value of displacement current is :

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5.50 A
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$5.56 \times 10^{2} A$
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5.56 $\times 10^{3}$ A
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$2.28 \times 10^{4} A$

In an electromagnetic wave, the direction of the magnetic field induction $\vec{B}$ is

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parallel to electric field $\vec{E}$
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perpendicular to electric field $\vec{E}$
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antiparallel to Poynting vector $\vec{S}$
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random

In an electromagnetic wave

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Power is transmitted along the magnetic field
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Power is transmitted along the electric field
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Power is equally transferred along with the electric and magnetic fields
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power is transmitted in a direction perpendicular to both the fields

For any E.M. wave if E = 100 V/m and the magnetising field is equal to 0.265 A/m. Then the rate of maximum energy flow per unit area is:

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$3.33 \times 10^{- 5} J / m^{2}$
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26.5 W/ $m^{2}$
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$3 \times 10^{8} J / m^{2}$
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None of these

A variable frequency AC source is connected to a capacitor. Then on increasing the frequency

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Both conduction current and displacement current will increase
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Both conduction current and displacement current will decrease
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Conduction current will increase and displacement will decrease
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Conduction current will decrease and displacement current will increase

Source of an electromagnetic wave is

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A charge moving with constant velocity
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A charge at rest
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A charge moving in a circular orbit
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Charges cannot produce an EM wave

The dimension of E/H is that of

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Impedance
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Inductance
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capacitance
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Inductance $\times$ Capacitance

Poynting vector $\vec{P}$ for an EM wave is :

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$\vec{P} = \vec{E} \times \vec{B}$
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$\vec{P} = \vec{E} \times \vec{H}$
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$\vec{P} = \frac{\vec{E}}{\vec{B}}$
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$\vec{P} = \frac{\vec{E}}{\vec{H}}$

Which one statement is incorrect about the electromagnetic waves?

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$\vec{E} \times \vec{B}$ gives always the direction of propagation
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$\vec{E}$ is always perpendicular to $\vec{B}$
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Transverse in nature
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$\vec{E}$ is always parallel to $\vec{B}$

Instantaneous displacement current of 2.0 A is set up in the space between two parallel plates of 1 $μ F$ capacitor. The rate of change in potential difference across the capacitor is-

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$3 \times 10^{6} V / s$
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$4 \times 10^{6} V / s$
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$2 \times 10^{6} V / s$
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none of these

Which one statement is incorrect?

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Speed of light in free space = $\frac{1}{\sqrt{μ_{0} \in_{0}}}$
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Speed of light in medium = $\frac{1}{\sqrt{μ \in}}$
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$\frac{E_{0}}{B_{0}} = c$
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$\frac{B_{0}}{E_{0}} = c$

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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