1. X-rays can pass through
X-rays can pass through Carbon andCalcium, but they are largely absorbed by (B) Gold and (C) Lead, with lead being the most effective in blocking X-rays.
2. ___ rays are used in the treatment of skin disorders.
Ultraviolet (UV) rays are used in the treatment of various skin disorders, such as psoriasis, eczema, and vitiligo, through phototherapy.
3. Protons and neutrons in the nucleus are called as
Nucleons refer to the protons and neutrons present in the nucleus of an atom.
4. Particles like mesons were discovered from
Mesons were first discovered in cosmic ray showers, where high-energy cosmic rays collide with atmospheric particles, creating secondary particles, including mesons.
Key Points:
Cosmic Ray Showers: High-energy cosmic rays from space interact with Earth's atmosphere, producing a cascade of secondary particles, including mesons.
Discovery of Mesons: The pion (π-meson) was first discovered in cosmic rays, confirming Yukawa's theory of nuclear forces.
5. Who named the ionising radiations from outer cosmos as cosmic rays?
Robert A. Millikan named the ionizing radiations from outer space as cosmic rays in the early 20th century while studying high-energy radiation penetrating the Earth's atmosphere.
6. The principle used in Atom bomb is
The atom bomb works on the principle of nuclear fission, where a heavy nucleus (like uranium-235 or plutonium-239) splits into smaller nuclei, releasing a huge amount of energy in the form of an explosion.
7. 1 amu is equal to
1 atomic mass unit (amu) is approximately 1.66 × 10⁻²⁷ kg, which is the average mass of a nucleon (proton or neutron) in an atom.
8. A good coolant possess
A good coolant should have:
Large specific heat capacity → To absorb and carry away more heat without a significant rise in temperature.
High boiling point → To remain in liquid form and function effectively at high temperatures without evaporating.
Example: Water is an excellent coolant because it has a high specific heat capacity and a high boiling point.
9. Energy of an electron when it is accelerated through a potential difference of 1 volt is
The energy gained by an electron when it is accelerated through 1 volt is defined as 1 electron volt (eV).
1 eV = 1.6 × 10⁻¹⁹ joules.
This is a fundamental unit of energy in atomic and particle physics.
10. The principle used in hydrogen bomb is
The hydrogen bomb (or thermonuclear bomb) works on the principle of nuclear fusion, where lighter nuclei (like isotopes of hydrogen – deuterium and tritium) fuse to form heavier nuclei, releasing an enormous amount of energy.
This process requires extremely high temperature and pressure, which is initially provided by a fission bomb (atomic bomb) as a trigger.
Fusion releases much more energy than fission, making hydrogen bombs far more powerful.
11. In electromagnetic interactions the exchange particle is
Electromagnetic interactions occur between charged particles (like electrons and protons).
These interactions are mediated by the exchange of photons (γ), which are the force carriers of the electromagnetic force in quantum electrodynamics (QED).
12. Mass defect is equal to
Mass defect is the difference between the total mass of individual nucleons and the actual nuclear mass. This lost mass is converted into binding energy, holding the nucleus together via
Einstein’s equation E = mc sqr
13. Thermal neutrons have energy of about
• Thermal neutrons are slow-moving neutrons that are in thermal equilibrium with their surroundings (usually at room temperature, around 300 K).
• Their typical energy is approximately 0.025 eV, which corresponds to their average kinetic energy given by:
E = 3/2kBT
where kB is Boltzmann’s constant and T is the temperature in Kelvin.
Thermal neutrons are crucial in nuclear reactors, as they efficiently induce fission in isotopes like Uranium-235.
14. One can distinguish a telescope from a microscope by observing
A telescope is generally much longer than a microscope. Telescopes are designed to observe distant objects, requiring long focal lengths, while microscopes have short focal lengths to magnify tiny nearby objects.
15. The catalyst in the Carbon-Nitrogen cycle is
In the Carbon-Nitrogen (C-N) cycle, which occurs in stars, carbon acts as a catalyst to facilitate the fusion of hydrogen into helium.
16. Microwaves are not generated by
A Coolidge tube is used to generate X-rays, not microwaves.
Microwaves are generated by magnetrons, klystrons, and traveling wave tubes (TWTs).
17. The diameter of the atomic nucleus is of the order of
The diameter of an atomic nucleus is typically in the range of 10⁻¹⁴ to 10⁻¹⁵ meters, whereas the entire atom is about 10⁻¹⁰ meters in size.
18. The energy released by the fission of one gram uranium is
The fission of 1 gram of uranium-235 releases a huge amount of energy, approximately 5.128 × 10²³ MeV or 22,600 kWh of electrical energy.
19. The part of the mass spectrometer which allows the iron beam of a particular velocity to pass through another slit is
The velocity selector ensures that only ions with a specific velocity pass through by using perpendicular electric and magnetic fields to filter out ions of different speeds.
20. The decrease in cosmic ray intensity at the earth’s equator is explained to be due to
The Earth's magnetic field deflects cosmic rays, causing a decrease in their intensity at the equator compared to the poles.
21. The cathode and anode terminals of GM tube are made up of _____ and _____ respectively.
In a Geiger-Müller (GM) tube, the cathode is typically made of a conductive metal like tungsten that forms the outer cylinder, while the anode is a thin wire, often made of aluminium or similar materials, running through the center.
22. The fuel to be used in prototype fast breedor reactor being built at Kalpakkam is mixture of
The Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, India, uses a mixed oxide (MOX) fuel, which is a combination of plutonium dioxide (PuO₂) and uranium dioxide (UO₂). This type of fuel helps in the efficient breeding of fissile material, making it a key component in India's nuclear energy program.
23. In Bainbridge mass spectrometer, the larger the radius of curvature of track
In a Bainbridge mass spectrometer, the radius of curvature (r) of the ion's path in the magnetic field is given by:
𝑟 = 𝑚𝑣 / 𝑞𝐵
where:
𝑚 = mass of the isotope
𝑣 = velocity of the isotope
𝑞 = charge of the isotope
𝐵 = magnetic field strength
Since radius (r) is directly proportional to mass (m), a larger radius means the isotope has a larger mass.
24. Which of the following is not electromagnetic in nature?
Electromagnetic waves include UV rays, gamma rays, and infrared rays, traveling as oscillating electric and magnetic fields. Alpha rays, consisting of helium nuclei, have mass and charge, making them particle radiation, not electromagnetic.
25. When a radioactive nucleus disintegrates by emitting a betta particle, its atomic number
When a radioactive nucleus emits a beta (β) particle, its atomic number increases by one because a neutron is converted into a proton and an electron (beta particle).
26. In fast breeder reactors, the fuel pellets are packed in special tubes made up of
In fast breeder reactors, the fuel pellets are packed in special tubes made of stainless steel because it can withstand high temperatures and radiation without corroding.
27. Who discovered Neutron?
The neutron was discovered by James Chadwick in 1932 through experiments involving beryllium bombarded with alpha particles.
28. X-rays could not be diffracted by ordinary grating on account of their
X-rays cannot be diffracted by ordinary gratings because their wavelength is too short compared to the grating spacing. Instead, crystals with atomic-scale spacing are used for X-ray diffraction studies.
29. When an energetic electron or positron present in cosmic rays collides with the nuclei of atoms in the earth’s atmosphere it loses energy in the form of
When an energetic electron or positron in cosmic rays collides with atomic nuclei in the Earth's atmosphere, it loses energy by emitting high-energy photons in a process called bremsstrahlung (braking radiation).
30. Geiger-Muller counter is used to measure the ______ of the radioactive radiation.
Geiger-Muller counter is used to measure the intensity of radioactive radiation by detecting and counting ionizing particles such as alpha, beta, and gamma rays.