EASY

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Which of the following radiations has the highest wave number ?

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Important Questions on Structure of Atom

MEDIUM

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

The power radiated by a black body is P and it radiates maximum energy at wavelength,

λ_{0}

. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength

\frac{3}{4} λ_{0}

, the power radiated by it becomes nP. The value of n is

HARD

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

A certain stellar body has radius

50 R_{s}

and temperature

2 T_{s}

and is at a distance of

2 \times 10^{10} AU

from the earth. Here,

AU

refers to the earth-sun distance and

R_{s}

and

T_{s}

refer to the sun's radius and temperature, respectively. Take, both star and sun to be ideal black bodies. The ratio of the power received on earth from the stellar body as compared to that received from the sun is close to

EASY

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

If the work function for the photoelectron emission of a metal is

3.75 eV

, then the threshold wave length of the radiation needed for the ejection of the electron is approximately

MEDIUM

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

If $p$ is the momentum of the fastest electron ejected from a metal surface after the irradiation of light having wavelength $λ,$ then for $1.5 p$ momentum of the photoelectron, the wavelength of the light should be:

(Assume kinetic energy of ejected photoelectron to be very high in comparison to work function)

EASY

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

The value of Planck's constant is

6 .63 \times 10^{- 34} Js

and the velocity of light is

3 .0 \times 10^{8} {ms}^{- 1}

. Which value is the closest to the wavelength in nanometers of a quantum of light, with a frequency of

8 \times 10^{15} s^{- 1}

MEDIUM

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

Which of the graphs shown below does not represent the relationship between incident light and the electron ejected from metal surface?

HARD

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

The "Kangri" is an earthen pot used to stay warm in Kashmir during the winter months. Assume that the "Kangri" is spherical and of surface area

7 \times 10^{- 2} m^{2} .

It contains

300 g

of a mixture of coal, wood and leaves with calorific value of

30 kJ g^{- 1}

(and provides heat with

10 %

efficiency). The surface temperature of the 'Kangri' is

60 ° C

and the room temperature is

0 ° C .

Then, a reasonable estimate for the duration t (in hours) that the 'kangri' heat will last is (take the 'kangri' to be a black body):

HARD

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

If the photon of wavelength

150 pm

strikes an atom and one of its inner bound electron is ejected out with a velocity of

1.5 \times 10^{7} m / s

, what is the energy with which it is bound to the nucleus?

EASY

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

Which of the following is the correct unit of angular momentum of an electron in an orbital of an atom ?

MEDIUM

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

A spherical black body with a radius of

12 cm

radiates

450 W

power at

500 K

. If the radius were halved and the temperature doubled, the power radiated in watt would be

EASY

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

Calculate the energy in corresponding to light of wavelength

45 n m :

(Planck’s constant

h = 6.63 \times 10^{- 34} J s : s p e e d o f l i g h t c = 3 \times 10^{8} m s^{- 1})

EASY

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

A particular station of All India Radio, New Delhi, broadcasts on a frequency of

1, 368 kHz

(kilo Hertz). The wavelength of the electromagnetic radiation emitted by the transmitter is [speed of light,

c = 3.0 \times 10^{8} {ms}^{- 1}

]

HARD

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

The work function of sodium metal is

4.41 \times 10^{- 19} J .

If photons of wavelength

300 nm

are incident on the metal, the kinetic energy of the ejected electrons will be

(h = 6.63 \times 10^{- 34} J s; c = 3 \times 10^{8} m s^{- 1})

__________

\times 10^{- 21} J

MEDIUM

Chemistry>Physical Chemistry>Structure of Atom>Dual Behaviour of Electromagnetic Radiation

What is the work function of the metal if the light of wavelength $4000 Å$ generates photoelectrons of velocity $6 \times 10^{5} {ms}^{- 1}$ from it?

(Mass of electron $= 9 \times 10^{- 31} kg$ , velocity of light $= 3 \times 10^{8} {ms}^{- 1}$ , Planck's constant $= 6 .626 \times 10^{- 34} Js$ , Charge of electron $= 6 .626 \times 10^{- 34} Js$ )