HARD

JEE Main

IMPORTANT

Earn 100

A special kind of light bulb emits monochromatic light of wavelength $630 nm .$ Electrical energy is supplied to it at the rate of $60 W$ and the bulb is $93 %$ efficient at converting that energy to light energy. How many photons are emitted by the bulb during its lifetime of $730 h ?$

Important Questions on Photons and Matter Waves

HARD

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 55

The stopping potential for electrons emitted from a surface illuminated by the light of wavelength

491 nm

0.710 V

. When the incident wavelength is changed to a new value, the stopping potential is

1.43 V

(a)

What is this new wavelength?

(b)

What is the work function for the surface?

MEDIUM

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 56

What is the photon energy for yellow light from a highway sodium lamp at a wavelength of

589 nm ?

HARD

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 58

You wish to pick an element for a photocell that will operate via the photoelectric effect with visible light. Which of the following are suitable, (work functions are in parentheses) tantalum

(4.2 eV),

tungsten

(4.5 eV),

aluminium

(4.2 eV),

barium

(2.5 eV),

lithium

(2.3 eV) ?

HARD

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 60

What is the maximum kinetic energy of electrons knocked out of a thin copper foil by Compton scattering of an incident beam of

18.3 keV

x

rays? Assume the work function is negligible.

HARD

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 61

Light strikes a sodium surface, causing photoelectric emission. The stopping potential for the ejected electrons is

5.0 V

and the work function of sodium is

2.2 eV .

What is the wavelength of the incident light?

HARD

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 62

(a)

MeV c^{- 1},

what is the magnitude of the momentum associated with a photon having an energy equal to the electron rest energy? What are the

(b)

wavelength and

(c)

frequency of the corresponding radiation?

HARD

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 64

In a photoelectric experiment using a sodium surface, you find a stopping potential of

1.85 V

for a wavelength of

300 nm

and a stopping potential of

0.820 V

for a wavelength of

400 nm .

From these data find

(a)

a value for the Planck constant,

(b)

the work function

Φ

for sodium and

(c)

the cut-off wavelength

λ_{0}

for sodium.

HARD

JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 36 - Photons and Matter Waves>Problems>Q 65

Assuming that your surface temperature is

98.6 ° F

and that you are an ideal blackbody radiator (you are close), find

(a)

the wavelength at which your spectral radiancy is maximum,

(b)

the power at which you emit thermal radiation in a wavelength range of

1.00 nm

at that wavelength, from a surface area of

4.00 {cm}^{2},

and

(c)

the corresponding rate at which you emit photons from that area. Using a wavelength of

500 nm

(in the visible range),

(d)

recalculate the power and

(e)

the rate of photon emission. (As you have noticed, you do not visibly glow in the dark).

A special kind of light bulb emits monochromatic light of wavelength 630 nm. Electrical energy is supplied to it at the rate of 60 W and the bulb is 93% efficient at converting that energy to light energy. How many photons are emitted by the bulb during its lifetime of 730 h?

Important Questions on Photons and Matter Waves

Learn and Prepare for any exam you want !

A special kind of light bulb emits monochromatic light of wavelength $630 nm .$ Electrical energy is supplied to it at the rate of $60 W$ and the bulb is $93 %$ efficient at converting that energy to light energy. How many photons are emitted by the bulb during its lifetime of $730 h ?$