Practice MCQ Questions and answers on Physics-GK

An alpha particle is identical to a helium atom that has been stripped of its two electrons; thus, an alpha particle contains two protons and two neutrons.

Atomic packing factor of body centred cubic structure (bcc) is 0.68.

To produce controlled energy i.e energy at a controlled or steady rate, the number of fissions per second must be controlled and maintained at that rate. Excess neutrons should be absorbed by control roads like cadmium.

All commercial power reactors are based on nuclear fission. They generally use uranium and its product plutonium as nuclear fuel, though a thorium fuel cycle is also possible.

Nuclear energy, also called atomic energy, energy that is released in significant amounts in processes that affect atomic nuclei, the dense cores of atoms. It is distinct from the energy of other atomic phenomena such as ordinary chemical reactions, which involve only the orbital electrons of atoms.

X-rays – smaller than 10 nano metre. Gamma- rays – 0.0005 to 0.1 nano metre. Alpha-rays – 125 nano metre.

It is a result of unstable atoms that are trying to stabilize. The excess energy is released as gamma particles. However, lead, steel and concrete reduce the energy of these particles and hence stop their penetrating abilities.

The atom bomb is based on the principle of nuclear fission.

The damage of the human body due to radiation (X-rays or gamma rays etc) is measured in rems.

Radioactivity is the release of energy and matter due to a change in the nucleus of an atom. Radioisotopes are isotopes that are unstable and release radiation. All isotopes are not radioisotopes. Transmutation occurs when a radioactive element attempts to become stabilized and transforms into a new element.