The electric field of a plane polarized electromagnetic wave in free space at time t = 0 is given by the expression E → x , y = 10 j ^ c o s 6 x + 8 z . The magnetic field B → x , z , t is given by ( c is the velocity of light.)

1 c 6 k ^ - 8 i ^ c o s 6 x + 8 z - 10 c t

1 c 6 k ^ - 8 i ^ cos 6 x + 8 z + 10 c t

1 c 6 k ^ + 8 i ^ cos 6 x + 8 z - 10 c t

1 c 6 k ^ + 8 i ^ cos 6 x - 8 z + 10 c t

EASY

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Assertion $(A) :$ Electromagnetic waves exert pressure, called radiation pressure. Reason $(R) :$ This is because they carry energy.

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Important Questions on Dual Nature of Matter and Radiation

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

The sound waves after converting into the electric waves are not directly transmitted because:

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A radiation of energy

E

falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (

C

= Velocity of light)

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

What do you understand by the statement, “Electromagnetic waves transport momentum”?

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

Sun light falls normally on a surface of area

36 {cm}^{2}

and exerts an average force of

7.2 \times 10^{- 9} N

within a time period of

20

minutes. Considering a case of complete absorption, the energy flux of incident light is

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

The radiation produced by a

100 W

bulb has the following property

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A point source of light emits isotropically with a power of $200 W$ . The light is incident normally on a perfectly reflecting circular surface of radius $2 cm$ at a distance of $20 m$ from the source. The force exerted by light on the surface is

Speed of light $c = 3 \times 10^{8} m s^{- 1}$

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

Light with an energy flux of

25 \times 10^{4} {W m}^{- 2}

falls on a perfectly reflecting surface at normal incidence. If the surface area is

15 {c m}^{2},

the average force exerted on the surface is:

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A red $L E D$ emits light at $0.1 watt$ uniformly around it. The amplitude of the electric field of the light at a distance of $1 m$ from the diode is:

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

Light with an energy flux of

120 W {cm}^{- 2}

falls on a normal reflecting surface at normal incidence. Find the average force exerted on the surface in

20 minutes

if the surface has an area of

2

square meter.

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

The electric field in a plane electromagnetic wave is given by

\vec{E} = 200 \cos [(0.5 \times 10^{3} m^{- 1}) x - (1.5 \times 10^{11} rad s^{- 1}) t] V m^{- 1} \hat{j}

.
If this wave falls normally on a perfectly reflecting surface having an area of

100 {cm}^{2}

. If the radiation pressure exerted by the E.M. wave on the surface during a

10 \min

exposure is

\frac{k}{10^{9}} N m^{- 2}

. Find the value of

k

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A light of intensity

12 W m^{- 2}

incidents on a black surface of area

4 {cm}^{2}

. The radiation pressure on the surface is

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

The mass of a hydrogen molecule is

3.32 \times 10^{- 27} kg .

10^{23}

hydrogen molecules strike, per second, a fixed wall of the area

2 {cm}^{2}

at an angle of

45^{o}

to the normal, and rebound elastically with a speed of

10^{3} m s^{- 1},

then the pressure on the wall is nearly:

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A beam of light with intensity

10^{- 3} N m^{- 2}

and cross sectional area

20 {cm}^{2}

is incident on a fully reflective surface at angle

45 °

. Then the force exerted by the beam on the surface is

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A laser pointer has an output power of

1 mW

and emits light of wavelength

660 nm

. if the beam from the pointer is incident normally on a perfectly reflecting mirror, the force exerted by the light beam on the mirror will be approximately,

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A beam of white light is incident normally on a plane surface absorbing

70 %

of the light and reflecting the rest. If the incident beam carries

10 W

of power, the force exerted by it on the surface is

HARD

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

The electric field of a plane polarized electromagnetic wave in free space at time

t = 0

is given by the expression

\vec{E} (x, y) = 10 \hat{j} c o s (6 x + 8 z)

. The magnetic field

\vec{B} (x, z, t)

is given by (

c

is the velocity of light.)

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

Out of the following options which one can be used to produce a propagating electromagnetic wave?

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

A light bulb of power

100 W

is placed at the centre of a hollow sphere of radius

10 cm .

If the

66 %

of the energy is converted into light, then the pressure exerted by the light on the surface of the sphere will be
(Assume the surface of sphere to be perfectly absorbing)

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

Sunlight of intensity

50 W m^{- 2}

is incident normally on the surface of a solar panel. Some part of incident energy (

25 %

) is reflected from the surface and the rest is absorbed. The force exerted on

1 m^{2}

surface area will be close to

(c = 3 \times 10^{8} m s^{- 1})

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Radiation Pressure

An electromagnetic wave of intensity

I

is incident on a non-reflecting surface. If

C

is the speed of light in free space, then the ratio

\frac{I}{C}

is same as

Assertion (A): Electromagnetic waves exert pressure, called radiation pressure. Reason (R): This is because they carry energy.

Important Questions on Dual Nature of Matter and Radiation

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Assertion $(A) :$ Electromagnetic waves exert pressure, called radiation pressure. Reason $(R) :$ This is because they carry energy.