CSIR Physical Sciences: Questions 238 - 240 of 389

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Question number: 238

» Thermodynamic and Statistical Physics » Random Walk

Appeared in Year: 2014

MCQ▾

Question

In one dimension, a random walker takes a step with equal probability to the left or right. What is the probability that the walker returns to the starting point after 4 steps? (June – 2014)

Choices

Choice (4) Response

a.

116

b.

38

c.

516

d.

14

Question number: 239

» Condensed Matter Physics » Free Electron Theory

Appeared in Year: 2014

MCQ▾

Question

The dispersion relation for electron in an f. c. c. crystal is given, in the tight binding approximation, by ε(k)=4ε0[coskxa2coskya2+coskya2coskza2+coskza2coskxa2] ; where a is the lattice constant and εo is a constant with the dimension of energy. The x – component of the velocity of the electrons at (πa,0, 0) is – (June – 2014)

Choices

Choice (4) Response

a.

4ε0a

b.

2ε0a

c.

4ε0a

d.

2ε0a

Question number: 240

» Electromagnetic Theory » Radiation- From Moving Charges

Appeared in Year: 2013

MCQ▾

Question

An oscillating current I(t)=I0exp(iωt) flows in the direction of the y – axis through a thin metal sheet of area 1.0cm2 kept in the xy plane. The rate of total energy radiated per unit area from the surfaces of the metal sheet at a distance of 100 m is – (June – 2013)

Choices

Choice (4) Response

a.

I02ω12πε0c3

b.

I02ω212πε0c3

c.

I0ω12πε0c3

d.

I0ω224πε0c3

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