UPSC Physics Optional PYQs (CSE & IFoS)PYQs

How much energy is required to separate {}_8^{16}\text{O} nucleus into its constituent nucleons ? What is the binding energy per nucleon for this nucleus ?

Describe the properties of field quanta of electro-weak and strong interactions of particles.

What are leptons? How are they different from other baryons? Define their quantum numbers and identify the forbidden ones in the following scattering or decay processes, justifying your conclusions :

(i) \pi^0 \rightarrow \gamma + \gamma

(ii) \pi^0 \rightarrow \gamma + \gamma \rightarrow (e^+ + e^-) + (\mu^- + \mu^+)

(iii) n \rightarrow p + e^- + \bar{\nu}_\mu

(iv) \pi^+ + p \rightarrow p + p + u_\tau + \bar{\nu}_e

(v) u_e + p \rightarrow u_\mu + p + \pi^0

What are the quantum numbers of u, d and s quarks and of the corresponding antiquarks (\bar{u}, \bar{d}, \bar{s})? Obtain the quark contents of proton (p), neutron (n), positively charged pion (\pi^+) and negatively charged omega minus (\Omega^-) particle.

What is parity transformation? Discuss the experiment that confirms the violation of parity in beta decay.

Give an outline of meson theory of nuclear forces. Describe the physical basis of short-range nuclear repulsion between like nucleons : proton-proton (p\text{-}p) or neutron-neutron (n\text{-}n). Consider the following two three-nucleon systems : (p\text{-}p\text{-}p) and (n\text{-}n\text{-}n). Which one is more likely to form a bound state?

Obtain the Q-values for the following four nuclear reactions :

(i) {}^{14}_{7}\text{N} + ^{4}_{2}\text{He} \rightarrow ^{17}_{8}\text{O} + ^{1}_{1}\text{H}

(ii) {}^{7}_{3}\text{Li} + ^{4}_{2}\text{He} \rightarrow ^{10}_{5}\text{B} + ^{1}_{0}\text{n}

(iii) {}^{6}_{3}\text{Li} + ^{1}_{1}\text{H} \rightarrow ^{3}_{2}\text{He} + ^{4}_{2}\text{He}

(iv) {}^{23}_{11}\text{Na} + ^{1}_{1}\text{H} \rightarrow ^{20}_{10}\text{Ne} + ^{4}_{2}\text{He}

In a nuclear fusion process, four hydrogen nuclei combine to form a helium nucleus. Obtain the energy released in such a process. If the same process is responsible for energy of a star of mass 2 \times 10^{30}\text{ kg}, each kilogram having 6 \times 10^{26} protons, what could be the magnitude of energy released in it?

Describe the quark model. Obtain the quark composition of baryons and mesons.

Discuss the four basic types of fundamental interactions in nature and compare them.

Obtain the ground-state wave function, depth of potential and range of nuclear force in deuteron and discuss. Also prove that no bound state exists for l \neq 0.

Discuss the shell model of the nucleus. What are its merits ?

Compute the density of a typical nucleus and find the resultant mass, if we could manufacture a nucleus with a radius of 1\text{ cm}.

What is kinematics of nuclear reaction ? What is the Q-value and its significance ?

How does the semi-empirical mass formula explain the stability of a nucleus against beta decay ?

Explain in detail the classification of elementary particles.

Explain why each of the following reactions is forbidden :

(i) p + p \rightarrow p + p + n

(ii) p + p \rightarrow p + \pi^+ + \gamma

(iii) \Xi^0 \rightarrow n + \pi^0

(iv) \Lambda \rightarrow p + \pi^0

(v) u_e + p \rightarrow n + e^+

What are the major components of a fission reactor ? With a schematic diagram explain its working.

Briefly explain the meson theory of nuclear force.

Calculate the energy released per gram of fuel for the nuclear reaction {}_1^2\text{H} + {}_1^2\text{H} \rightarrow {}_1^3\text{H} + {}_1^1\text{H}