Home
Class 12
PHYSICS
Calculate the intensity and the rms valu...

Calculate the intensity and the rms value of electric field of electromagnetic waves at a distance 10 m from a 100 W electric bulb . Given `in_0=8.85xx10^(-12)F.m^(-1)`

Text Solution

Verified by Experts

Area of a spherical surface of radius 10 m
`=4pi(10)^2=400pim^2`
`therefore` Intensity , I,=`"100 W"/(400 pi m^2)=1/(4pi) W.m^(-2)=0.08 W.m^(-2)`
Here , `I=1/2cin_0E_0^2=cin_0E_"rms"^2 [ because E_"rms"=E_0/sqrt2]`
`therefore E_"rms"=sqrt(1/(cin_0))=sqrt((0.08)/((3xx10^8)xx(8.85xx10^(-12))))`
`=5.5V.m^(-1)`
Promotional Banner

Topper's Solved these Questions

  • ELECTROMAGNETIC WAVES

    CHHAYA PUBLICATION|Exercise SECTION RELATED QUESTIONS|14 Videos

  • ELECTROMAGNETIC WAVES

    CHHAYA PUBLICATION|Exercise HOTS QUESTIONS|5 Videos

  • ELECTROMAGNETIC INDUCTION & ALTERNATING CURRENT

    CHHAYA PUBLICATION|Exercise CBSE SCANNER|28 Videos

  • ELECTROMAGNETISM

    CHHAYA PUBLICATION|Exercise CBSE SCANNER|26 Videos

Similar Questions

Explore conceptually related problems

Find out the energy content in a volume of 1 cm^3 around a point, situated in the electric field of a point charge of 10C, at a distance of 2 m in air from the position of the point charge. Given, in_0 = 8.85 xx10^(-12)F*m^(-1) .

In a region of free space the average electric field of an electromagnetic wave is 9 xx 10^-4 NC^-1 . What is the magnetic field in that region?

Average intensity of the solar energy incident on the earth's surface is 1300 W.m^(-2) . Calculate the rms values of electric and magnetic fields due to this radiation near the earth's surface. (Given mu_0=4pixx10^(-7)H.m^(-1) )

A red LED emits light a 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is

Electromagnetic waves propagate through free space or a medium as transverse waves. The electric and magnetic fields are perpendicular to each other as well as perpendicular to the direction of propagation of waves at each point. In the direction of wave propagation, electric field vecE and magnetic field vecB form a right-handed cartesian coordinate system. During the propagation of electromagnetic wave, total energy of electromagnetic wave is distributed equally between electric and magnetic fields. Since in_0 and mu_0 are permittivity and permeability of free space, the velocity of electromagnetic wave, c=(in_0 mu_0)^(-1//2) . Energy density i.e., energy in unit volume due to electric field at any point, u_E=1/2in_0E^2 Similarly, energy density due to magnetic field , u_M=1/(2mu_0)B^2 . If the electromagnetic wave propagates along x-direction, then the equations of electric and magnetic field are respectively. E=E_0sin(omegat-kx) and B=B_0sin(omegat-kx) Here, the frequency and the wavelength of oscillating electric and magnetic fields are f=omega/(2pi) and lambda=(2pi)/k respectively. Thus E_"rms"=E_0/sqrt2 and B_"rms"=B_0/sqrt2 , where E_0/B_0=c . Therefore, average energy density baru_E=1/2in_0E_"rms"^2 and baru_M=1/(2mu_0)B_"rms"^2 . The intensity of the electromagnetic wave at a point, I=cbaru=c(baru_E+baru_B) . To answer the following questions , we assume that in case of propagation of electromagnetic wave through free space, c=3xx10^8 m.s^(-1) and mu_0=4pixx10^(-7) H.m^(-1) If the peak value of electric field at a point in electromagnetic wave is 15 V . m^(-1) , then average electrical energy density (in j . m^(-3) )

Amplitude of electric field of a plane electromagnetic wave is 48 V. m^(-1) . What is the amplitude of the magnetic field of the wave ?

When the frequency of an electromagnetic wave and the amplitude of its associated magnetic field at a point are 10^8 Hz and 10^(-10) T respectively, then the amplitude of electric field be nxx10^(-2) V.m^(-1) . Find the value of n.

A rectangular parallel plate capacitor of dimension 5 cm x 4 cm is charging in such a way that the rate of change of electric field between the two plates is 5.65xx10^11 V. m^(-1) .s^(-1) . Calculate the displacement current for this capacitor . Given in_0=8.85xx10^(-12) F.m^(-1)

CHHAYA PUBLICATION-ELECTROMAGNETIC WAVES -CBSE SCANNER
  1. Calculate the intensity and the rms value of electric field of electro...

    Text Solution

    |

  2. What are the directions of electric and magnetic field vectors relativ...

    Text Solution

    |

  3. The speed of an electromagnetic wave in a material medium is given by ...

    Text Solution

    |

  4. Welders wear special goggles or face masks with glass windows to prote...

    Text Solution

    |

  5. A capacitor made of two parallel plates each of plate area A and separ...

    Text Solution

    |

  6. To which part of the electromagnetic spectrum does a wave of frequency...

    Text Solution

    |

  7. Define intensity of radiation on the basis of photon picture of light....

    Text Solution

    |

  8. Which one of the following electromagnetic radiations has least freque...

    Text Solution

    |

  9. How do you show that electromagnetic waves carry energy and momentum?

    Text Solution

    |

  10. Write the expression for the energy density of an electromagnetic wave...

    Text Solution

    |

  11. How are electromagnetic waves produced? What is the source of energy o...

    Text Solution

    |

  12. Why does current in a steady state not flow in a capacitor connected a...

    Text Solution

    |

  13. How is the speed of EM waves in vacuum determined by the electric and ...

    Text Solution

    |

  14. Do electromagnetic waves carry energy and momentum?

    Text Solution

    |

  15. Identify the electromagnetic waves whose wavelengths vary as (a)10^(...

    Text Solution

    |

  16. What do you understand by the statement, "Electromagnetic waves transp...

    Text Solution

    |

  17. Name the electromagnetic radiations used for (a) Water purification (...

    Text Solution

    |

  18. Why are infrared waves often called heat waves? Explain.

    Text Solution

    |