Which radiation has no electric charge associated with it?
A. Alpha rays
B. Beta rays
C. Gamma rays
D. All of these
E. None of these
The correct answer and explanation is:
Correct Answer: C. Gamma rays
Gamma rays are a form of electromagnetic radiation, much like visible light, but they carry much more energy. Unlike alpha and beta particles, gamma rays are not composed of particles with mass or charge. They are purely energy in the form of photons and thus carry no electric charge.
To understand this better, consider the three main types of nuclear radiation:
- Alpha particles (α-rays) consist of two protons and two neutrons. This gives them a +2 charge because they have two positively charged protons and no electrons to balance them. Due to their charge and relatively large mass, alpha particles are strongly ionizing but can be stopped by a sheet of paper or even skin.
- Beta particles (β-rays) are high-energy, high-speed electrons (beta-minus) or positrons (beta-plus) emitted from a decaying atomic nucleus. Electrons carry a negative charge (-1), while positrons carry a positive charge (+1). These particles are lighter than alpha particles and more penetrating, but still have mass and charge.
- Gamma rays (γ-rays), on the other hand, are electromagnetic waves released from the nucleus after radioactive decay has occurred, often alongside alpha or beta emissions. Gamma rays have no mass and no charge, which makes them electrically neutral. Because of this, gamma rays do not ionize matter as strongly as alpha or beta particles, but they are highly penetrating and require dense materials like lead or several centimeters of concrete to be effectively blocked.
Gamma rays are commonly used in medical treatments like cancer radiotherapy, industrial imaging, and sterilization of equipment due to their strong penetrating ability. Their lack of electric charge makes them different from other types of radiation and defines their unique behavior in electric and magnetic fields, where they remain unaffected.