The beam from an argon laser (of wavelength 515 nm ) has a diameter d of 3 . 00 mm and a continuous energy output rate of 4 . 00 W . The beam is focused onto a diffuse surface by a lens whose focal length f is 3 . 50 cm . A diffraction pattern is formed, the radius of the central disk being given by R = 1 . 22 f λ d . The central disk can be shown to contain 84 % of the incident power. ( a ) What is the radius of the central disk? ( b ) What is the average intensity (power per unit area) in the incident beam? ( c ) What is the average intensity in the central disk?

( a ) The radius of the central disk is R = 1 . 22 f λ d = ( 1 . 22 ) ( 3 . 50 cm ) ( 515 nm ) 3 . 00 mm = 7 . 33 μ m . ( b ) The average power flux density in the incident beam is P π d 2 / 4 = 4 ( 4 . 00 W ) π ( 3 . 00 mm ) 2 = 5 . 65 × 10 5 W m - 2 . ( c ) The average power flux density in the central disk is ( 0 . 84 ) P π R 2 = ( 0 . 84 ) ( 4 . 00 W ) π ( 7 . 33 μ m ) 2 = 1 . 99 × 10 10 W m - 2 .

MEDIUM

JEE Main

IMPORTANT

Earn 100

A pulsed laser emits light at a wavelength of $694.4 nm .$ The pulse duration is $12 ps,$ and the energy per pulse is $0.150 J .$ $(a)$ What is the length of the pulse? $(b)$ How many photons are emitted in each pulse?

Important Questions on All About Atoms

EASY

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 20

From Figure

40 - 13,

calculate approximately the energy difference,

E_{L} - E_{M}

, for molybdenum. Compare it with the value that may be obtained from Figure

40 - 15 .

EASY

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 21

A helium-neon laser emits laser light at a wavelength of

632.8 nm

and a power of

2.3 mW .

At what rate are photons emitted by this device?

EASY

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 22

For a helium atom in its ground state, what are quantum numbers

(n, l, m_{l}, m_{s})

for the

(a)

spin-up electron and

(b)

spin-down electron?

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IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 24

15 keV

electron is brought to rest by colliding twice with target nuclei(Assume the nuclei remain stationary.). The wavelength associated with the photon emitted in the second collision is

130 pm

greater than that associated with the photon emitted in the first collision.

(a)

What is the kinetic energy of the electron after the first collision? What are

(b)

the wavelength

λ_{1}

and

(c)

the energy

E_{1}

associated with the first photon? What are

(d)

λ_{2}

and

(e)

E_{2}

associated with the second photon?

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JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 26

A laser emits

424 nm

in a single pulse that lasts

0.500 μs

. The power of the pulse is

3.25 MW .

If we assume that the atoms contributing to the pulse underwent stimulated emission only once during the

0.500 μs,

how many atoms contributed?

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JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 27

X-rays are produced in an x-ray tube by electrons accelerated through an electric potential difference of

50.0 kV .

Let

K_{0}

be the kinetic energy of an electron at the end of the acceleration. The electron collides with a target nucleus (Assume the nucleus remains stationary.) and then, has kinetic energy

K_{1} = 0.500 K_{0}

(a)

What wavelength is associated with the photon that is emitted? The electron collides with another target nucleus (Assume it, too, remains stationary.) and then, has kinetic energy

K_{2} = 0.500 K_{1} .

(b)

What wavelength is associated with the photon that is emitted?

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IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 28

The beam from an argon laser (of wavelength $515 nm$ ) has a diameter $d$ of $3.00 mm$ and a continuous energy output rate of $4.00 W .$ The beam is focused onto a diffuse surface by a lens whose focal length $f$ is $3.50 cm .$ A diffraction pattern is formed, the radius of the central disk being given by $R = \frac{1.22 f λ}{d}$ . The central disk can be shown to contain $84 %$ of the incident power. $(a)$ What is the radius of the central disk? $(b)$ What is the average intensity (power per unit area) in the incident beam? $(c)$ What is the average intensity in the central disk?

EASY

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 37 - All About Atoms>Problems>Q 29

Assume that lasers are available whose wavelengths can be precisely "tuned" to anywhere in the visible range, i.e., in the range $450 nm < λ < 650 nm .$ If every television channel occupies a bandwidth of $10 MHz,$ how many channels can be accommodated within this wavelength range?

A pulsed laser emits light at a wavelength of 694.4 nm. The pulse duration is 12 ps, and the energy per pulse is 0.150 J. (a) What is the length of the pulse? (b) How many photons are emitted in each pulse?

Important Questions on All About Atoms

Learn and Prepare for any exam you want !

A pulsed laser emits light at a wavelength of $694.4 nm .$ The pulse duration is $12 ps,$ and the energy per pulse is $0.150 J .$ $(a)$ What is the length of the pulse? $(b)$ How many photons are emitted in each pulse?