CSIR Physical Sciences: Questions 384 - 387 of 401

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Question number: 384

» Electromagnetic Theory » Laplace and Poisson Equations

Appeared in Year: 2011

MCQ▾

Question

A static, spherically symmetric charge distribution is given by ρ(r)=Arekr , where A and K are positive constants. The electrostatic potential corresponding to this charge distribution varies with r as, (June)

Choices

Choice (4) Response

a.

reKr

b.

1r2eKr

c.

1r(1eKr)

d.

1reKr

Passage

1.6×1019 Chromium ions cubic centimeter. All the atoms excited by the 0.4μm radiation decay rapidly to level E2 which has a lifetime τ=3ms

Three energy levels for Chromium ions

Three Energy Levels for Chromium Ions

In figure three distinct energy levels are shown. All atoms excited by radiation decay.

(June)

Question number: 385 (1 of 2 Based on Passage) Show Passage

» Atomic & Molecular Physics » Optical Pumping

Appeared in Year: 2011

MCQ▾

Question

The minimum pump power required (per cubic centimeter) to bring the system to transparency, i. e. , zero gain, is –

Choices

Choice (4) Response

a.

2.64kW

b.

1.52kW

c.

0.76kW

d.

1.32kW

Question number: 386 (2 of 2 Based on Passage) Show Passage

» Atomic & Molecular Physics » Population Inversion

Appeared in Year: 2011

MCQ▾

Question

Assuming that there is no radiation of wavelength 0.7μm present in the pumping cycle and that the pumping rate is R atoms per cm3 , the population density in the level N2 builds up as:

Choices

Choice (4) Response

a.

N2(t)=Rt2τ(1etτ)

b.

N2(t)=Rτ(etτ1)

c.

N2(t)=Rt

d.

N2(t)=Rτ(1etτ)

Passage

In the absence of an applied torque a rigid body with three distances principal moments of inertia given by I1,I2andI3 is rotating freely about a fixed point inside the body. The Euler equations for the components of its angular velocity (ω1,ω2,ω3) are

ω˙1=I2I1I1ω2ω3,ω˙2=(I3I1)I2ω1ω3,ω˙3=I1I2I3ω1ω2 (June)

Question number: 387 (1 of 2 Based on Passage) Show Passage

» Classical Mechanics » Rigid Body Dynamics - Moment of Inertia Tensor

Appeared in Year: 2011

MCQ▾

Question

The constant of motion are –

Choices

Choice (4) Response

a.

I1ω12+I2ω22+I3ω32andω1+ω2+ω3

b.

I1ω12+I2ω22+I3ω32andI12ω12+I22ω22+I32ω32

c.

ω12+ω22+ω32andI1ω1+I2ω2+I3ω3

d.

ω12+ω22+ω32andI12ω12+I22ω22+I32ω32

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