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Two hydrogen atoms are in excited state with electrons residing in $n = 2 .$ First one is moving towards left and emits a photon of energy $E_{1}$ towards right. Second one is moving towards right with same speed and emits a photon of energy $E_{2}$ towards right. Taking recoil of nucleus into account during emission process

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Important Questions on Modern Physics - I

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 5

In a hydrogen atom following the Bohr's postulates the product of linear momentum and angular momentum is proportional to

(n)^{x}

where

' n'

is the orbit number. Then

' x'

is:

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 7

The wavelengths of

K_{α} x -

rays of two metals

' A'

and

' B'

are

\frac{4}{1875 R}

and

\frac{1}{675 R}

respectively, where

R

is Rydberg's constant. The number of elements lying between

' A'

and

' B'

according to their atomic numbers is

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 8

One of the lines in the emission spectrum of

L i^{2 +}

has the same wavelength as that of the

2^{nd}

line of Balmer series in hydrogen spectrum. The electronic transition corresponding to this line is:

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 9

If the short wavelength limit of the continuous spectrum coming out of a Coolidge tube is

10 \overset{°}{A},

then the de-Broglie wavelength of the electrons reaching the target metal in the Coolidge tube is approximately:

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 10

The photon radiated from hydrogen corresponding to

2^{nd}

line of Lyman series is absorbed by a hydrogen like atom

' X'

2^{nd}

excited state. As a result the hydrogen like atom

' X'

makes a transition to

n^{th}

orbit. Then,

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 11

In a photoelectric experiment, with light of wavelength

λ,

the fastest electron has speed

v .

If the exciting wavelength is changed to

\frac{3 λ}{4},

the speed of the fastest emitted electron will become

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 12

The element which has a $K_{α}$ $X -$ rays line of wavelength $1.8 Å$ is $(R = 1.1 \times 10^{7} m^{- 1}, b = 1$ and $\sqrt{5 / 33} = 0.39)$

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 11 - Modern Physics - I>Exercise#1>Q 13

When an electron accelerated by potential difference $U$ is bombarded on a specific metal, the emitted $X -$ ray spectrum obtained is shown in adjoining graph. If the potential difference is reduced to $\frac{U}{3},$ the correct spectrum is

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Important Questions on Modern Physics - I

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