MEDIUM

Earn 100

A cobalt (atomic no. $= 27$ ) target is bombarded with electrons and the wave lengths of its characteristic $X$ -rays spectrum are measured. A second weak characteristic spectrum is also found due to an impurity in the target. The wavelength of the $K_{α}$ lines are $225.0 pm$ (cobalt) and $100.0 pm$ (impurity). Atomic number of the impurity is

50% studentsanswered this correctly

Important Questions on Atomic Physics

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

An X-ray tube is operated at

1.24

million volt. The shortest wavelength of the produced photon will be:

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

Electrons of mass,

m

with de-Broglie wavelength,

λ

fall on the target in an X-ray tube. The cutoff wavelength,

(λ_{0})

of the emitted X-ray is

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

W. K. Roentgen discovered

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

The shortest wavelength of

X

-rays emitted from an

X

-ray tube depends upon

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

The frequency of

K_{a}

line of a source of atomic number

z

is proportional to

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

Which wave or ray is produced due to decelerating or accelerating charged particles?

MEDIUM

Physics>Modern Physics>Atomic Physics>Moseley’s Law

An electron beam is accelerated by a potential difference

V

to hit a metallic target to produce

X -

rays. It produces continuous as well as characteristic

X -

rays. If

λ_{m i n}

is the smallest possible wavelength of

X -

ray in the spectrum, the variation of

\log (λ_{m i n})

with

\log (V)

is correctly represented in :

MEDIUM

Physics>Modern Physics>Atomic Physics>Moseley’s Law

In an

X

-ray tube, electrons emitted from a filament (cathode) carrying current

I

hit a target (anode) at a distance

d

from the cathode. The target is kept at a potential

V

higher than the cathode resulting in emission of continuous and characteristic X-rays. If the filament current

I

is decreased to

\frac{I}{2},

the potential difference

V

is increased to

2 V,

and the separation distance

d

is reduced to

\frac{d}{2},

then

HARD

Physics>Modern Physics>Atomic Physics>Moseley’s Law

The

K_{α}

X-ray of molybdenum has wavelength

0.071 nm

. If the energy of a molybdenum atom with a

K

electron knocked out is

27.5 keV

, the energy of this atom when an

L

electron is knocked out will be

keV

. (Round off to the nearest integer )

[h = 4.14 \times 10^{- 15} eV s, c = 3 \times 10^{8} {m s}^{- 1}]

MEDIUM

Physics>Modern Physics>Atomic Physics>Moseley’s Law

In a diffraction pattern due to a single slit of width

' a'

, the first minimum is observed at an angle

30 °

when light of wavelength

500 nm

is incident on the slit. The first secondary maximum is observed at an angle of

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

The waves emitted when a metal target is bombarded with high energy electrons are

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

The luminous border that surrounds the profile of a mountain just before sun rises behind it, is an example of

HARD

Physics>Modern Physics>Atomic Physics>Moseley’s Law

A plane electromagnetic wave of frequency

25 G H z

is propagating in vacuum along the z-direction. At a particular point in space and time, the magnetic filed is given by

\vec{B} = 5 \times 10^{- 8} T \hat{j} .

The corresponding electric field

\vec{E}

is (speed of light

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

)

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

Wavelength of characteristic X-ray depends on which property of target?

(where, A = Mass number, Z = Atomic number)

MEDIUM

Physics>Modern Physics>Atomic Physics>Moseley’s Law

The electric field of a plane electromagnetic wave is given by

\vec{E} = E_{0} \frac{\hat{i} + \hat{j}}{\sqrt{2}} \cos (k z + ω t)

. At

t = 0

, a positively charged particle is at the point

(x, y, z) = (0, 0, \frac{π}{k})

. If its instantaneous velocity at

(t = 0)

v_{0} \hat{k}

, the force acting on it due to the wave is:

MEDIUM

Physics>Modern Physics>Atomic Physics>Moseley’s Law

A plane electromagnetic wave of frequency

50 M H z

travels in free space along the positive

x

- direction. At a particular point in space and time,

\vec{E} = 6.3 \hat{j} V / m,

The corresponding magnetic field

\vec{B}

, at that point will be:

EASY

Physics>Modern Physics>Atomic Physics>Moseley’s Law

The Nobel laureate ABDUS SALAM is known for discovery of

MEDIUM

Physics>Modern Physics>Atomic Physics>Moseley’s Law

K_{α}

radiation of

M o (Z = 42)

has a wavelength

0.71 \overset{o}{A}

, then the wavelength of the corresponding radiation of

C u (Z = 29)

HARD

Physics>Modern Physics>Atomic Physics>Moseley’s Law

A student is jogging on a straight path with the speed $5.4 km$ per hour. Perpendicular to the path is kept a pipe with its opening $8 m$ from the road (see figure). Diameter of the pipe is $0.45 m$ At the other end of the pipe is a speaker emitting sound of $1280 Hz$ towards the opening of the pipes. As the student passes in front of the pipe, she hears the speaker sound for $T$ seconds. $T$ is in the range (take speed of sound, $320 {ms}^{- 1}$ ):

Question Image

MEDIUM

Physics>Modern Physics>Atomic Physics>Moseley’s Law

λ_{Cu}

is the wavelength of

K_{α}

X -

ray line of copper (atomic number

29

) and

λ_{M o}

is the wavelength of the

K_{α}

X -

ray line of molybdenum (atomic number

42

), then the ratio

\frac{λ_{Cu}}{λ_{M o}}

is close to

Important Questions on Atomic Physics

Learn and Prepare for any exam you want !