EmSAT Physics Flashcards

What is the half-life of a radioactive substance?

Answer: The time for half the atoms to decay

Half-life is the time required for half of the radioactive atoms in a sample to decay. After one half-life, 50% remains; after two, 25%; and so on.

Which type of radiation is most penetrating?

Answer: Gamma rays

Gamma rays are the most penetrating type of nuclear radiation. They are electromagnetic waves that can pass through most materials and require thick lead or concrete to block.

What is nuclear fission?

Answer: Splitting a heavy nucleus into smaller nuclei

Nuclear fission is the process of splitting a heavy atomic nucleus (like uranium-235) into smaller nuclei, releasing a large amount of energy. It is the basis of nuclear reactors.

What does E = mc² represent?

Answer: Mass-energy equivalence

Einstein's famous equation E = mc² expresses mass-energy equivalence: mass (m) can be converted to energy (E), and vice versa. c is the speed of light, making even small masses equivalent to enormous energy.

What charge does a proton have?

Answer: Positive

A proton carries a positive charge of +1.6 × 10⁻¹⁹ coulombs. Neutrons are neutral and electrons are negatively charged.

What is the atomic number of an element?

Answer: Number of protons in the nucleus

The atomic number is the number of protons in the nucleus of an atom. It uniquely identifies a chemical element and determines its position on the periodic table.