Hydrogen H 1 1 , deuterium H 2 1 , singly ionised helium He 4 2 + and doubly ionised lithium Li 8 3 + + all have one electron around the nucleus. Consider an electron transition from n = 2 to n = 1 . If the wavelengths of emitted radiation are λ 1 , λ 2 , λ 3 and λ 4 , respectively for four elements, then approximately which one of the following is correct?

4 λ 1 = 2 λ 2 = 2 λ 3 = λ 4

λ 1 = 2 λ 2 = 3 λ 3 = 4 λ 4

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IMPORTANT

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Assertion- If light continuously falls on a metal surface, then the emission of electrons will stop after some time.

Reason- We cannot extract all the electrons of a metal.

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Important Questions on Modern Physics

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JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 20

Assertion- Ionization power of $α$ -particles is maximum while penetration power of $γ$ -rays is maximum.

Reason- $α$ -particles are the heaviest particles, while $γ$ -rays have maximum energy.

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JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 1

A metal surface is illuminated by the light of two different wavelengths

248 nm

and

310 nm

. The maximum speeds of the photoelectrons corresponding to these wavelengths are

u_{1}

and

u_{2}

, respectively. If the ratio

u_{1} : u_{2} = 2 : 1

and

h c = 1240 eV nm

, the work function of the metal is nearly

HARD

JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 2

The radiation corresponding to

3 \to 2

transition of the hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field of

3 \times 10^{- 4} T

. If the radius of the largest circular path followed by these electrons is

10.0 mm

, the work function of the metal is close to

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JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 3

Hydrogen

({}_{1}H^{1})

, deuterium

({}_{1}H^{2})

, singly ionised helium

{({}_{2}{He}^{4})}^{+}

and doubly ionised lithium

{({}_{3}{Li}^{8})}^{+ +}

all have one electron around the nucleus. Consider an electron transition from

n = 2

n = 1

. If the wavelengths of emitted radiation are

λ_{1}

λ_{2}

λ_{3}

and

λ_{4}

, respectively for four elements, then approximately which one of the following is correct?

EASY

JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 4

During the propagation of electromagnetic waves in a medium

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JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 5

What is the de-Broglie wavelength of the electron accelerated through a potential difference of

100 V

EASY

JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 6

The maximum kinetic energy of the photoelectrons depends only on

EASY

JEE Advanced

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 2>Chapter 9 - Modern Physics>Objective Problems [Level 2]>Q 7

The relation between the half-life

T_{(1 / 2)}

and decay constant

λ

Assertion- If light continuously falls on a metal surface, then the emission of electrons will stop after some time. Reason- We cannot extract all the electrons of a metal.

Important Questions on Modern Physics

Learn and Prepare for any exam you want !

Assertion- If light continuously falls on a metal surface, then the emission of electrons will stop after some time.

Reason- We cannot extract all the electrons of a metal.