Question
Write characteristics of electro magnetic waves.
✓
Answer
Characteristics of EM waves are as follows :
(1) In EM wave, the electric field, magnetic field and direction of wave propogation are mutually perpendicular.
(2) Relationship between the values / magnitudes of electric field and magnetic field in EM wave is :
$\frac{ E _0}{B_0}=c \text { or } \frac{ E _{ rms }}{ B _{ rms }}=c$
(3) EM waves are transverse and non-mechanical waves.
(4) Velocity of EM waves in vacuum, $c=\frac{1}{\sqrt{\mu_0 \varepsilon_0}}$
where, $\mu_0$ - permeability of free space
$\varepsilon_0$ - permittivity of free space
→Velocity of EM waves in medium, $v=\frac{1}{\sqrt{\mu \varepsilon}}$ where, $\mu$ - permeability of medium $\varepsilon$ - permittivity of medium
(5) As demonstrated by scientist Hertz, the EM waves experience diffraction, refraction and polarisation.
(6) EM waves are polarized.
(7) EM waves possess and carry energy, which is known as radiation energy.
(8) When an EM wave strikes (/ is incident) on a surface, it exerts pressure, which is called radiation pressure.
(9) Direction of $\vec{E} \times \vec{B}$ shows the direction of propogation of wave.
(10) In the region of space far from the source, the oscillations of electric field and magnetic field vectors are in phase.
(11) Energy density in EM wave, $\varrho=\varepsilon_0 E _{\text {rms }}^2$ and $\varrho=\frac{ B _{\text {rms }}^2}{\mu_0}$.
(1) In EM wave, the electric field, magnetic field and direction of wave propogation are mutually perpendicular.
(2) Relationship between the values / magnitudes of electric field and magnetic field in EM wave is :
$\frac{ E _0}{B_0}=c \text { or } \frac{ E _{ rms }}{ B _{ rms }}=c$
(3) EM waves are transverse and non-mechanical waves.
(4) Velocity of EM waves in vacuum, $c=\frac{1}{\sqrt{\mu_0 \varepsilon_0}}$
where, $\mu_0$ - permeability of free space
$\varepsilon_0$ - permittivity of free space
→Velocity of EM waves in medium, $v=\frac{1}{\sqrt{\mu \varepsilon}}$ where, $\mu$ - permeability of medium $\varepsilon$ - permittivity of medium
(5) As demonstrated by scientist Hertz, the EM waves experience diffraction, refraction and polarisation.
(6) EM waves are polarized.
(7) EM waves possess and carry energy, which is known as radiation energy.
(8) When an EM wave strikes (/ is incident) on a surface, it exerts pressure, which is called radiation pressure.
(9) Direction of $\vec{E} \times \vec{B}$ shows the direction of propogation of wave.
(10) In the region of space far from the source, the oscillations of electric field and magnetic field vectors are in phase.
(11) Energy density in EM wave, $\varrho=\varepsilon_0 E _{\text {rms }}^2$ and $\varrho=\frac{ B _{\text {rms }}^2}{\mu_0}$.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Explain the dependence of the electric potential generated at a great distance due to a small electric dipole, when the point of observation is (i) in the axial position, and (ii) in the equatorial position.
Answer the following question:
Ray optics is based on the assumption that light travels in a straight line. Diffraction effects (observed when light propagates through small apertures/slits or around small obstacles) disprove this assumption. Yet the ray optics assumption is so commonly used in understanding location and several other properties of images in optical instruments. What is the justification?
Ray optics is based on the assumption that light travels in a straight line. Diffraction effects (observed when light propagates through small apertures/slits or around small obstacles) disprove this assumption. Yet the ray optics assumption is so commonly used in understanding location and several other properties of images in optical instruments. What is the justification?
Why is the luminous efficiency small for a filament bulb as compared to a mercury vapour lamp?
Explain : "Electric charges are additive in nature."
Find the flux of the electric field through a spherical surface of radius R due to a charge of 10-7C at the centre and another equal charge at a point 2R away from the centre.
Write the formula for the force per unit length between two parallel current carrying wires. Using it, write the definition of Ampere and Coulomb.
In the Rutherford's nuclear model of the atom, the nucleus (radius about $10^{-15} m$ ) is analogous to the sun about which the electron move in orbit (radius $\approx 10^{-10} m$ ) like the earth orbits around the sun. If the dimensions of the solar system had the same proportions as those of the atom, would the earth be closer to or farther away from the sun than actually it is? The radius of earth's orbit is about $1.5 \times 10^{11} m$. The radius of sun is taken as $7 \times 10^8 m$.
→The angles of dip at two places located on the earth are 0° and 90° respectively. Where are the places located?
Find the thermo-emf developed in a copper-silver thermocouple when the junctions are kept at 0°C and 40°C. Use the data in table.
| |||||||||||||||||||||||||||
|
Under what condition, force on moving charged particle in a magnetic field will be (i) maximum (ii) minimum?