Solve your IGNOU Doubts

Question:

Depict spatial evolution of Fresnel diffraction pattern.

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Question:

Discuss the concept of missing orders with reference to double slit diffraction pattern.

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Question:

Describe polarisation of light by reflection. How does degree of polarisation vary with angle of incidence of light?

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Question:

The sodium lamp used in a physics laboratory gives out light uniformly. Suppose that the lamp uses 40 W. Calculate the magnitude of electric field.

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Question:

wo tritium ( $^3_1\text{H}$ ) nuclei fuse to release 11.3 MeV energy. Calculate the total energy released in the fusion of 1 kg tritium.

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Question:

From the semi-empirical mass formula, calculate the value of the atomic number (Z) for the most stable nucleus at a given mass number A. Calculate Z₀ for $A = 90$ .

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Question:

Calculate the kinetic energy of the alpha particle emitted in the alpha decay of the Radium isotope $^{226}_{88}\text{Ra}$ ( $^{226}_{88}\text{Ra} \rightarrow ^{222}_{86}\text{Rn} + {}^4_2\text{He}$ ). It is given that
$m(^{226}_{88}\text{Ra}) = 226.0254\text{ u}$ , $m({}^4_2\text{He}) = 4.0026\text{ u}$ and $m(^{222}_{86}\text{Rn}) = 222.0176\text{ u}$ .

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Question:

The half-life of $^{14}\text{C}$ is known to be 5730 years. Calculate the decay constant (in $\text{s}^{-1}$ ). Also, calculate the rate of disintegration for 1 g of $^{14}\text{C}$ .

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Question:

An electron with a energy of 8.0 eV strikes a potential barrier of energy 12.0 eV. If the tunnelling probability is 4.0 percent, determine the width of the barrier.

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Question:

Explain whether the eigen functions of the following Hamiltonian for a particle of mass m will have a definite parity: $H = \frac{p^2}{2m} + \frac{1}{2}m\omega^2x^2$ .

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Question:

Calculate the probability current density of the incident and reflected waves for the quantum mechanical particle incident on a step potential
$$V(x) = \begin{cases} 0 & , x < 0 \\ V_0 > 0 & , x > 0 \end{cases}$ $
when E < V₀.

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Question:

The eigenfunction of a particle confined in a box of length L ( $0 \le x \le L$ ) is
$$\psi_n(x) = \sqrt{\frac{2}{L}} \sin\left( \frac{n \pi x}{L} \right)$ $
i) Show that $\psi_n(x)$ is not an eigenfunction of the momentum operator.
ii) Calculate the expectation value of the kinetic energy.

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Question:

The normalized wave function for a particle is given by
$$\psi(x) = \begin{cases} 2a\sqrt{a}\text{ }x\text{ }e^{-ax}, & x > 0 \\ 0, & x < 0 \end{cases}$ $
Determine
i) the value of x at which the probability density function is maximum, and
iii) the probability of finding the particle between $x = 0$ and $x = 1/a$ .

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Question:

The average decay life time of an elementary particle is $1.0\text{ }\mu\text{s}$ . Calculate the minimum uncertainty in the measurement of its energy. Also, calculate the minimum uncertainty in the measurement of its mass using the mass-energy equivalence.

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Question:

Electrons are accelerated through $150\text{V}$ and incident on a crystal with interatomic spacing $d = 0.25\text{ nm}$ . Calculate the de Broglie wavelength and the first-order Bragg diffraction angle.

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Question:

In a photoelectric effect experiment, it is seen that when light of wavelength $180\text{ nm}$ is incident on a metal, the measured photoelectric current drops to zero at a potential $-1.00\text{ V}$ . Calculate the work function of the metal and its cut-off frequency for photoelectric effect.

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Question:

An electric field of $10^6\text{ Vm}^{-1}$ is applied along the direction of motion of an electron moving with a speed of 0.6c. Calculate the acceleration of the electron.

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Question:

A particle moves with speed 0.8c. Calculate its momentum, kinetic energy and total energy.

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Question:

A star emits light of wavelength $500\text{ nm}$ and recedes from Earth at speed 0.50c. Calculate the observed wavelength.

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Question:

A spaceship approachin Earth at a speed c/2, shoots a canister at a speed of 0.80c. Calculate the velocity of the canister for an observer on Earth if (i) the canister if it is shot directly toward Earth and (ii) if it is shot directly away from Earth.

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