Atoms and Nuclei (KVPY (Kishore Vaigyanik Protsahan Yojana) Stream SB-SX (Class 12 & 1st Year B.Sc.) Physics): Questions 11 - 13 of 14

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Question number: 11

» Atoms and Nuclei » Binding Energy Per Nucleon

Appeared in Year: 2014

MCQ▾

Question

A solid sphere slipping about a horizontal axis with an angular velocity ω is placed on a horizontal surface. Subsequently it rolls without slipping with an angular velocity of –

Choices

Choice (4) Response

a.

Equation

b.

Equation

c.

Equation

d.

ω

Question number: 12

» Atoms and Nuclei » Bohr Model

Appeared in Year: 2015

MCQ▾

Question

A donor atom in a semiconductor has a loosely bound electron. The orbit of this electron is considerably affected by the semiconductor material but behaves in many ways like an electron orbiting a hydrogen nucleus. Given that the electron has an effective mass of 0.07me, (where me is mass of the electron) and the space in which it moves has a permittivityEquation , then the radius of the electron’s lowermost energy orbit will be close to (The Bohr radius of the hydrogen atom is 0.53 Å)

Choices

Choice (4) Response

a.

10 Å

b.

100 Å

c.

243 Å

d.

0.53 Å

Question number: 13

» Atoms and Nuclei » Radioactivity

Appeared in Year: 2015

MCQ▾

Question

Carbon -11 decays to boron -11 according to the following formula.

Equation

Assume that positrons (e+) produced in the decay combine with free electron in the atmosphere and annihilate each other almost immediately. Also assume that the neutrinos (νe) are massless and do not interact with the environment. At t = 0 we have 1 µg ofEquation . If the half-life of the decay process is t0, the net energy produced between time t = 0 and t = 2t0 will be nearly,

Choices

Choice (4) Response

a.

Equation

b.

Equation

c.

Equation

d.

Equation

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