Physics — Nuclear Science

Control rods are used to absorb excess neutrons, thereby controlling or stopping the chain reaction in a nuclear reactor.

Nuclear fusion is the process where two light atomic nuclei combine to form a heavier nucleus, which is also the source of energy in stars.

U-235 is fissile, meaning it can sustain a nuclear chain reaction, making it the primary fuel for nuclear reactors.

James Chadwick discovered the neutron, a subatomic particle with no electric charge, in 1932.

Henri Becquerel discovered radioactivity in 1896 while investigating uranium salts.

Coolants (like water, gas, or liquid metal) are circulated to remove the heat generated by the nuclear reaction to produce steam.

Gamma rays are high-energy electromagnetic waves with the highest penetrating power, requiring thick lead or concrete to shield.

The Becquerel (Bq) is the SI unit of radioactivity, defined as one decay per second.

Fusion requires extremely high temperatures to overcome electrostatic repulsion, hence it is called a thermonuclear reaction.

Carbon-14 undergoes beta decay to transform into Nitrogen-14.

Half-life is the time required for a quantity of a radioactive isotope to reduce to half of its initial value.

Plutonium-239 is commonly used as fuel in fast breeder reactors to produce more fissile material than they consume.

The Sun generates energy through the nuclear fusion of hydrogen nuclei into helium in its core.

A Geiger-Müller counter is a standard instrument used to detect and measure ionizing radiation.

Alpha decay results in the loss of 2 protons and 2 neutrons, decreasing the atomic number by 2 and the mass number by 4.

Niels Bohr proposed the liquid drop model, which visualizes the nucleus as a drop of incompressible nuclear fluid.

Critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction.

Radio waves have low energy and do not have enough energy to ionize atoms, unlike X-rays or alpha particles.

Iron-56 has one of the highest binding energies per nucleon, making it one of the most stable nuclei.

The Sievert (Sv) is the SI unit of radiation dose equivalent, used to measure the health effect of low levels of ionizing radiation on the human body.

A reflector surrounds the core of a nuclear reactor to scatter neutrons that would otherwise escape back into the fuel region, thereby increasing the efficiency of the chain reaction.

Lead is highly effective at shielding gamma radiation because of its high atomic number and high density, which increases the probability of absorbing high-energy photons.

The CNO cycle is a catalytic cycle of nuclear fusion in stars where Carbon, Nitrogen, and Oxygen nuclei act as catalysts to convert hydrogen into helium.

Einstein's mass-energy equivalence (E=mc²) explains that the mass defect in a nuclear reaction is converted into energy.

In beta-minus decay, a neutron inside the nucleus converts into a proton and emits an electron (beta particle) and an antineutrino.

Heavy water (D2O) contains deuterium, an isotope of hydrogen, and is used as a moderator and coolant because it has a low absorption cross-section for neutrons.

An atomic bomb relies on an uncontrolled nuclear fission chain reaction, resulting in a rapid and massive release of energy.

Dr. Homi J. Bhabha was the visionary physicist who established the Tata Institute of Fundamental Research and the Bhabha Atomic Research Centre.

An alpha particle is a helium nucleus (2 protons, 2 neutrons). Emitting it reduces the parent's mass number by 4 and atomic number by 2.

Radiocarbon dating (Carbon-14) is used to estimate the age of organic materials based on the known decay rate of the isotope.

In beta-plus decay, a proton turns into a neutron, emitting a positron and a neutrino to conserve lepton number.

Nuclear fusion releases significantly more energy per unit mass than fission, as it involves the binding of light nuclei into a more stable, higher-binding-energy state.

The Nuclear Shell Model suggests that nucleons exist in energy levels similar to electrons, explaining why nuclei with 'magic numbers' of protons or neutrons are exceptionally stable.

The Geiger-Müller counter is a standard instrument used for detecting and measuring ionizing radiation by ionising the gas within its tube.

A breeder reactor is designed to produce more fissile material (like Plutonium-239 from Uranium-238) than it consumes, extending the availability of nuclear fuel.

Radioactivity is the process by which an unstable atomic nucleus loses energy by radiation.

Iodine-131 is commonly used in nuclear medicine to diagnose and treat conditions related to the thyroid gland.

Binding energy represents the energy equivalent of the mass defect; it is the energy needed to disassemble a nucleus into its constituent nucleons.

The strong nuclear force is one of the fundamental forces of nature and is the short-range, powerful attraction that overcomes the electrostatic repulsion between protons in the nucleus.

The primary fuel in the Sun is Hydrogen-1, which fuses to form Helium-4, releasing vast amounts of energy.

Mass defect is the difference between the sum of the masses of individual nucleons (protons and neutrons) and the actual measured mass of the nucleus, which accounts for the binding energy.

Thermal or slow neutrons have a higher probability of being captured by Uranium-235 nuclei, triggering the fission process effectively.

The Curie (Ci) is a non-SI unit of radioactivity, defined as the quantity of a radioactive nuclide that decays at a rate of 3.7 × 10^10 disintegrations per second.

Beta decay (the transformation of a neutron into a proton or vice versa) is governed by the weak nuclear force.

Alpha decay reduces the atomic number by 2 and the mass number by 4. Uranium-238 (Z=92) becomes Thorium-234 (Z=90).

The outward thermal pressure generated by thermonuclear fusion in the core of a star balances the inward pull of gravity.

Niels Bohr introduced the liquid drop model in 1936, which describes the nucleus as a drop of incompressible nuclear fluid.

Cladding (usually Zircaloy) encapsulates the fuel pellets to prevent corrosion and leakage of radioactive fission products into the coolant.

An alpha particle is identical to a helium nucleus (two protons and two neutrons), hence it has a charge of +2 and an atomic mass of 4.