Advertisements
Advertisements
प्रश्न
An EM wave of intensity I falls on a surface kept in vacuum and exerts radiation pressure p on it. Which of the following are true?
- Radiation pressure is `I/c` if the wave is totally absorbed.
- Radiation pressure is `I/c` if the wave is totally reflected.
- Radiation pressure is `(2I)/c` if the wave is totally reflected.
- Radiation pressure is in the range `I/c < p < (2I)/c` for real surfaces.
विकल्प
a, b and c
b, c and d
a, c and d
c and d
उत्तर
a, c and d
Explanation:
Radiation pressure (p) is the force exerted by electromagnetic waves on unit area of the surface, i.e., rate of change of momentum per unit area of the surface.
Let us consider a surface exposed to electromagnetic radiation as shown in figure. The radiation is falling normally on the surface. Further, intensity of radiation is I and area of surface exposed to radiation is A.
Radiation pressure is the force exerted by particles (dual nature of particle) on unit area, due to the charge in momentum of radiated particles per unit area per sec = `I/c`.
I = Intensity pf radiation
C = Velocity of radiation
Radiations are absorbed, so momentum per unit area second = `I/c`.
When radiation is reflected back, the momentum becomes double as in earlier case.
So variation of radiation pressure p comes between the range `I/c < p < (2I)/c`.
APPEARS IN
संबंधित प्रश्न
Write mathematical expressions for electric and magnetic fields of an electromagnetic wave propagating along the z-axis.
In a microwave oven, the food is kept in a plastic container and the microwaves is directed towards the food. The food is cooked without melting or igniting the plastic container. Explain.
A plane electromagnetic wave is passing through a region. Consider (a) electric field (b) magnetic field (c) electrical energy in a small volume and (d) magnetic energy in a small volume. Construct the pairs of the quantities that oscillate with equal frequencies.
Define frequency modulation and state any one advantage of frequency modulation (FM) over amplitude modulation (AM).
If the magnetic monopole exists, then which of the Maxwell’s equation to be modified?
Write down Maxwell equations in integral form.
Let an electromagnetic wave propagate along the x-direction, the magnetic field oscillates at a frequency of 1010 Hz and has an amplitude of 10-5 T, acting along the y – direction. Then, compute the wavelength of the wave. Also write down the expression for the electric field in this case.
Plane electromagnetic waves are ______.
A linearly polarized electromagnetic wave given as E = Eoî cos (kz – ωt) 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 ______.
The diagram below shows the electric field (E) and magnetic field (B) components of an electromagnetic wave at a certain time and location.
The direction of the propagation of the electromagnetic wave is ______.
