Class 12 ISC Physics Board Questions Chapter Mass Energy Equivalence

Class 12 ISC Physics Mass Energy Equivalence Board Questions

Here we provide Class 12 Physics important notes,board questions and predicted questions with Answers for chapter Mass Energy Equivalence. These important notes,board questions and predicted questions are based on ISC board curriculum and correspond to the most recent Class 12 Physics syllabus. By practising these Class 12 materials, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 12 Board examinations as well as other entrance exams such as NEET and JEE.

Select Option

Important Notes

Board Questions

Mass Energy Equivalence BoardQuestions

Q1 What is pair production?

solutions

Q2 What is meant by mass defect?

solutions

Q3 What is meant by pair annhilation? What is balance equation for the same.

solutions

When an electron and positron come close to each other they annihilate each other to produce two γ−photons.

Here mass is converted to energy.

The equation for this process can be given as : _-1β⁰ + ₊₁β⁰ =hν(photon)+hν(photon)

Here, two photons are produced so that both energy and momentum are conserved.

Q4 Sketch a graph showing variation of binding energy per nucleon of a nucleus with its mass number.

solutions

The graph between binding energy per nucleon versus mass number explains stability of nucleus.

At lower mass number the binding energy per nucleon increases with increasing mass number.

But, at higher mass number, the binding energy per nucleon decreases with increasing mass number.

This decrease is due to the increasing number of protons inside the nucleus in high mass numbers.

More protons lead to more Coulomb repulsion, thereby decreasing stability.

The graph can be given as follows:

Here, even-even nuclei such as carbon, helium and oxygen, are more stable than their immediate neighbours.

This is evident from the sharp rising peaks present in the graph.

Q5 For a radioactive substance, write the relation between :

(i) Half life (T) and disintegration constant (λ)
(ii) Mean life (τ) and disintegration constant (λ)

solutions

Q6 Calculate binding energy of oxygen nucleus ((₈¹⁶)O ) from the data given below :

Mass of proton = 1.007825 u , Mass of neutron = 1.008665 u , Mass of ((₈¹⁶)O )=15.994915 u

solutions

Mass of hydrogen atom is 1.007825 u
Mass of neutron is 1.008665 u
Atomic mass of ₈O¹⁶ is 15.994915 u

Now, binding energy is given as:
BE=Δm×931.5MeV
Substituting mass defect :
BE=[8×1.007825+8×1.00865−15.994915]×931.5
BE=0.1368×931.5 MeV
BE=127.42 MeV

Now, total number of nucleons are 16 (since 8 protons and 8 neutrons), so binding energy of nucleus is 127.42 MeV.
Then, binding energy per nucleon is :
BE per nucleon=127.42/16
BE per nucleon=7.964 MeV

Q7 What is the minimum energy which a gamma ray photon must possess in order to produce electron-positron pair?

solutions

1.02MeV

Q8 Calculate mass defect and binding energy per nucleon of ₁₀Ne²⁰ given

Mass of ₁₀Ne²⁰ = 19.992397 u.
Mass of ₁H¹ = 1.007825 u.
Mass of ₀n¹ = 1.008665 u.

solutions

Class 12 ISC Physics Mass Energy Equivalence Board Questions

Select Option

1.02MeV

Add a comment

Reach Us

SERVICES

CONTACT