Electromagnetic Waves
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Questions and Answers

What is the displacement current in a capacitor?

  • Sum of conduction and displacement currents
  • Current due to the magnetic field
  • Current due to the changing electric field (correct)
  • Current due to the flow of charges in a conductor

What is the relationship between the conduction current and the displacement current in a circuit?

  • They are independent of each other
  • Their sum is always continuous (correct)
  • They are always opposite in direction
  • They are always equal

What is the direction of the electric vector in an electromagnetic wave?

  • Perpendicular to the direction of propagation (correct)
  • Parallel to the direction of propagation
  • Perpendicular to the electric field
  • Parallel to the magnetic field

What is Faraday's law of electromagnetic induction?

<p>∫B.dl = -dφB / dt (B)</p> Signup and view all the answers

Who was the first to predict the existence of electromagnetic waves?

<p>Maxwell (A)</p> Signup and view all the answers

What is the intensity of the electromagnetic wave given in the problem?

<p>6 W/m² (D)</p> Signup and view all the answers

What is the maximum value of electric field at a distance 3.5 m from the source?

<p>62.6 V/m (B)</p> Signup and view all the answers

What is the value of magnetic field at a distance 3.5 m from the source?

<p>2.09 × 10⁻⁶ T (B)</p> Signup and view all the answers

What is the displacement current through the capacitor?

<p>2πnq₀ cos(2πnt) (B)</p> Signup and view all the answers

What is the value of magnetic field between the plates of the capacitor, at a distance of 1m from the centre?

<p>5.56 μT (D)</p> Signup and view all the answers

What is the primary mechanism by which X-rays are produced?

<p>Fast moving electrons being suddenly stopped by a metal target of high atomic number (D)</p> Signup and view all the answers

What is the characteristic of electromagnetic waves that allows them to propagate without a material medium?

<p>They are transverse waves (C)</p> Signup and view all the answers

What is the relationship between the energy density of the electric field and the magnetic field in an electromagnetic wave?

<p>ue = uB (A)</p> Signup and view all the answers

What is the speed of electromagnetic waves in free space?

<p>3 × 10^8 m/s (A)</p> Signup and view all the answers

What is the intensity of an electromagnetic wave equal to?

<p>ε0E^2 (A)</p> Signup and view all the answers

What is the unit of the Poynting vector S?

<p>Watt/m² (B)</p> Signup and view all the answers

If an electromagnetic wave of energy u is totally reflected from a surface, what is the momentum delivered to the surface?

<p>2u / c (B)</p> Signup and view all the answers

What is the intensity of an electromagnetic wave equal to?

<p>E² / (μ₀c) (A)</p> Signup and view all the answers

What is the radiation pressure on a perfectly absorbing surface?

<p>S.c (A)</p> Signup and view all the answers

What is the energy density of an electromagnetic wave equal to?

<p>E² / (2ε₀) (C)</p> Signup and view all the answers

What is the total population covered by the TV telecast if the average population density around the tower is 1000 / Km 2?

<p>39.5 × 10 5 (D)</p> Signup and view all the answers

If the energy of an electromagnetic radiation is 14.4 KeV, what is the corresponding wavelength?

<p>0.8 × 10 -10 m (A)</p> Signup and view all the answers

What is the unit of radiation pressure?

<p>N/m 2 (B)</p> Signup and view all the answers

If the intensity of an electromagnetic wave is 800 W/m 2, what is the corresponding Poynting vector?

<p>2667 N/m 2 (A)</p> Signup and view all the answers

What is the momentum of an electromagnetic wave per unit area per unit time?

<p>Intensity divided by c (A)</p> Signup and view all the answers

What is the ratio of the energy density of the magnetic field to the energy density of the electric field in an electromagnetic wave?

<p>1:1 (A)</p> Signup and view all the answers

What is the direction of the Poynting vector in an electromagnetic wave?

<p>Perpendicular to the electric field (C)</p> Signup and view all the answers

What is the physical significance of the intensity of an electromagnetic wave?

<p>The energy flux per unit area (D)</p> Signup and view all the answers

What is the relationship between the radiation pressure of an electromagnetic wave and its intensity?

<p>The radiation pressure is proportional to the intensity (D)</p> Signup and view all the answers

What is the momentum of an electromagnetic wave?

<p>Proportional to the energy density of the wave (D)</p> Signup and view all the answers

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