Dual Nature of Matter and Radiation (KVPY Stream SB-SX (Class 12 & 1st Year BSC) Physics): Questions 15 - 18 of 19

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Question number: 15

» Dual Nature of Matter and Radiation » Photoelectric Effect

Appeared in Year: 2014

MCQ▾

Question

A 160 watt light source is radiating light of wavelength 6200 Å uniformly in all directions. The photon flux at a distance of 1.8 m is of the order of (Planck’s constant 6.63 × 10–34 J-s)

Choices

Choice (4) Response

a.

1025m2s1

b.

1019m2s1

c.

102m2s1

d.

1012m2s1

Question number: 16

» Dual Nature of Matter and Radiation » Photoelectric Effect

MCQ▾

Question

When ultraviolet radiation of a certain frequency falls on a potassium target, the photoelectrons released can be stopped completely by a retarding potential of 0.9 V. If the frequency of the radiation is increased by 15%, this stopping potential rises to 1.2 V. The work function of potassium is –

Choices

Choice (4) Response

a.

2.0 eV

b.

1.5 eV

c.

2.8 eV

d.

1.1 eV

Question number: 17

» Dual Nature of Matter and Radiation » De-Broglie Relation

Appeared in Year: 2016

MCQ▾

Question

Electrons accelerated from rest by an electrostatic potential are collimated and sent through a Young’s double slit setup. The fringe width is w . If the accelerating potential is doubled then the width is now close to –

Choices

Choice (4) Response

a.

0.7w

b.

2.0w

c.

1.0w

d.

0.5w

Question number: 18

» Dual Nature of Matter and Radiation » Particle Nature of Light

Appeared in Year: 2016

MCQ▾

Question

Photons of wavelength λ are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular are of radius R by a perpendicular magnetic field having a magnitude B . The work function of the metal is –

(Where symbols have their usual meanings)

Choices

Choice (4) Response

a.

hcλme+e2B2R22me

b.

hcλ2me(eBR2me)2

c.

hcλ+2me(eBR2me)2

d.

hcλmec2e2B2R22me

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