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The magnetic field of a beam emerging from a filter facing a floodlight is given by B0 = 12 × 10–8 sin (1.20 × 107z – 3.60 × 1015t) T. What is the average intensity of the beam?

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प्रश्न

The magnetic field of a beam emerging from a filter facing a floodlight is given by B0 = 12 × 10–8 sin (1.20 × 107z – 3.60 × 1015t) T. What is the average intensity of the beam?

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उत्तर

The standard equation of magnetic field can be expressed as B = B0 sin ωt.

We are given equation B = 12 × 10–8 sin (1.20 × 107z – 3.60 × 1015t) T.

On comparing this equation with standard equation, we get

B0 = 12 × 10–8 T

The average intensity of the beam

`I_(av) = 1/2 B_0^2/mu_0 * c = 1/2 xx ((12 xx 10^-8)^2 xx 3 xx 10^8)/(4pi xx 10^-7)`

= 1.71 W/m2

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अध्याय 8: Electromagnetic Waves - MCQ I [पृष्ठ ५०]

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एनसीईआरटी एक्झांप्लर Physics Exemplar [English] Class 12
अध्याय 8 Electromagnetic Waves
MCQ I | Q 8.18 | पृष्ठ ५०

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