Magnetic field of a beam emerging from a filter facing a floodlight is given by B {B

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8.Electromagnetic waves

easy

The magnetic field of a beam emerging from a filter facing a floodlight is given by B${B_0} = 12 \times {10^{ - 8}}\,\sin \,(1.20 \times {10^7}\,z - 3.60 \times {10^{15}}t)T$. What is the average intensity of the beam ?

Option A

Option B

Option C

Option D

Solution

Comparing $\mathrm{B}=12 \times 10^{-8} \sin \left(1.20 \times 10^{7} z-3.60 \times 10^{15} t\right)$ with equation $\mathrm{B}=\mathrm{B}_{0} \sin \omega t$ $\mathrm{B}_{0}=12 \times 10^{-8} \mathrm{~T}$

Average intensity of beam,

$\mathrm{I}_{\text {average }}=\frac{\mathrm{B}_{0}^{2}}{2 \mu_{0}} \mathrm{C}$

$=\frac{1}{2} \times \frac{\left(12 \times 10^{-8}\right)^{2} \times 3 \times 10^{8}}{4 \times 3.14 \times 10^{-7}}$

$\therefore I_{\text {average }} =1.71 \mathrm{~W} / \mathrm{m}^{2}$

Standard 12

Physics

Identify the correct statements from the following descriptions of various properties of electromagnetic waves.

$A$. In a plane electromagnetic wave electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field.

$B.$ The energy in electromagnetic wave is divided equally between electric and magnetic fields.

$C.$ Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave.

$D.$ The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other.

$E.$ The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light.

Choose the most appropriate answer from the options given below:

medium

(JEE MAIN-2022)

A charged particle oscillates about its mean equilibrium position with a frequency of $10^9\ Hz$. The electromagnetic waves produced:

easy

A plane electromagnetic wave is travelling in the positive $X-$axis. At the instant shown electric field at the extremely narrow dashed rectangle is in the $-ve$ $z$ direction and its magnitude is increasing. Which diagram correctly shows the direction and relative magnitudes of magnetic field at the edges of rectangle :-

medium

The speed of electromagnetic wave in a medium (whose dielectric constant is $2.25$ and relative permeability is $4$ ) is equal to ………. $\times 10^8 \,m / s$

easy

The magnetic field of a plane electromagnetic wave is given by $\overrightarrow{ B }=3 \times 10^{-8} \cos \left(1.6 \times 10^3 x +48 \times 10^{10} t \right) \hat{ j }$, then the associated electric field will be :

medium

(NEET-2022)

The magnetic field of a beam emerging from a filter facing a floodlight is given by B${B_0} = 12 \times {10^{ - 8}}\,\sin \,(1.20 \times {10^7}\,z - 3.60 \times {10^{15}}t)T$. What is the average intensity of the beam ?

Solution

Similar Questions

A charged particle oscillates about its mean equilibrium position with a frequency of $10^9\ Hz$. The electromagnetic waves produced:

The speed of electromagnetic wave in a medium (whose dielectric constant is $2.25$ and relative permeability is $4$ ) is equal to ………. $\times 10^8 \,m / s$

The magnetic field of a plane electromagnetic wave is given by $\overrightarrow{ B }=3 \times 10^{-8} \cos \left(1.6 \times 10^3 x +48 \times 10^{10} t \right) \hat{ j }$, then the associated electric field will be :

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