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The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is
(a) C:1
(b) c2:1
(c) 1:1
(d) :1
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is
(a) C:1
(b) c2:1
(c) 1:1
(d) :1
This is a multiple choice answer as classified in NCERT Exemplar
(c) As from the relation that electric and magnetic energy density are equal to one another so there ratio will be always 1:1
Upvote 
If E and B represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along
(a) E
(b) B
(c) B×E
(d) E×B
If E and B represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along
(a) E
(b) B
(c) B×E
(d) E×B
This is a multiple choice answer as classified in NCERT Exemplar
(d) The direction of propagation of electromagnetic wave is perpendicular to both electric field vector E and magnetic field vector B, i.e., in the direction of E×B .
This can be seen by the diagram given below
Upvote The electric field intensity produced by the radiations coming from a 100 W bulb at a 3 m distance is E. The electric field intensity produced by the radiations coming from 50 W bulb at the same distance is
(a) E/2
(b) 2E
(c) E/√2
(d) E
The electric field intensity produced by the radiations coming from a 100 W bulb at a 3 m distance is E. The electric field intensity produced by the radiations coming from 50 W bulb at the same distance is
(a) E/2
(b) 2E
(c) E/√2
(d) E
This is a multiple choice answer as classified in NCERT Exemplar
(c) E
= =
2= E/
Upvote Light with an energy flux of 20 W/cm2 falls on a non-reflecting surface at normal incidence. If the surface has an area of 30 cm2, the total momentum delivered (for complete absorption) during 30 min is
(a) 36 x 10-5 kg-m/s
(b) 36 x 10-4 kg-m/s
(c) 108 x 104 kg-m/s
(d) 1.08 x 107 kg-m/s
Light with an energy flux of 20 W/cm2 falls on a non-reflecting surface at normal incidence. If the surface has an area of 30 cm2, the total momentum delivered (for complete absorption) during 30 min is
(a) 36 x 10-5 kg-m/s
(b) 36 x 10-4 kg-m/s
(c) 108 x 104 kg-m/s
(d) 1.08 x 107 kg-m/s
This is a multiple choice answer as classified in NCERT Exemplar
(b) as we know momentum = energy transferred/speed of light
= = 36 10-4kgms-1
Momentum of reflected light =0
So momentum delivered is = 36 10-4kgms-1
Upvote A linearly polarised electromagnetic wave given as E= E0icos(kz-wt) is incident normally on a perfectly reflecting infinite wall at z=a. assuming that the material of the wall is optically inactive, the reflected wave will be given as
(a) Er=Eoi(kz-wt)
(b) Er =Eoicos(kz+wt
(c) Er = -Eoicos(kz+wt)
(d) Er = Eoisin(kz-wt)
A linearly polarised electromagnetic wave given as E= E0icos(kz-wt) is incident normally on a perfectly reflecting infinite wall at z=a. assuming that the material of the wall is optically inactive, the reflected wave will be given as
(a) Er=Eoi(kz-wt)
(b) Er =Eoicos(kz+wt
(c) Er = -Eoicos(kz+wt)
(d) Er = Eoisin(kz-wt)
This is a multiple choice answer as classified in NCERT Exemplar
(b) the electromagnetic wave is
Er = Eoicos (kz-wt)
And reflected wave is given by
Er = -E0 (-i)cos (k (-z)+wt+ )
Upvote One requires 11 eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in
(a) Visible region
(b) Infrared region
(c) Ultraviolet region
(d) Microwave region
One requires 11 eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in
(a) Visible region
(b) Infrared region
(c) Ultraviolet region
(d) Microwave region
This is a multiple choice answer as classified in NCERT Exemplar
(c) E=hv
V= = 2.65 1015hz this belongs to uv region
Upvote Even though an electric field E exerts a force qE on a charged particle yet electric field of an EM wave does not contribute to the radiation pressure (but transfers energy). Explain.
Even though an electric field E exerts a force qE on a charged particle yet electric field of an EM wave does not contribute to the radiation pressure (but transfers energy). Explain.
This is a short answer type question as classified in NCERT Exemplar
Since, electric field of an EM wave is an oscillating field and so is the electric force caused by it on a charged particle. This electric force averaged over an integral number of cycles is zero, since its direction changes every h
Upvote What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of room, its intensity essentially remains constant. What geometrical characteristic of LASER beam is responsible for the constant intensity which is missing in the case of light from the bulb?
What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of room, its intensity essentially remains constant. What geometrical characteristic of LASER beam is responsible for the constant intensity which is missing in the case of light from the bulb?
This is a short answer type question as classified in NCERT Exemplar
As the distance is doubled, the area of spherical region ( 4πr2 )
will become four times, so the intensity becomes one fourth the initial value but in case of laser it does not spread, so its intensity remain same.
Geometrical charact
Upvote Show that the radiation pressure exerted by an EM wave of intensity I on a surface kept in vacuum is I/C.
Show that the radiation pressure exerted by an EM wave of intensity I on a surface kept in vacuum is I/C.
This is a short answer type question as classified in NCERT Exemplar
Pressure = force/area
Force =dp/dt
U=p.C or p= U/c
Pressure =
Pressure = I/C
Upvote You are given a 2 μF parallel plate capacitor. How would you establish an instantaneous displacement current of 1 mA in the space between its plates?
You are given a 2 μF parallel plate capacitor. How would you establish an instantaneous displacement current of 1 mA in the space between its plates?
This is a short answer type question as classified in NCERT Exemplar
q=CV
And we know q=It
Then Iddt= cdV
Id= Cdv/dt
1 = 2 10-6 dV/dt
DV/dt= 500V/s, this will produce the desired result.
Upvote