The correct option is **A. beta rays**. ### Detailed Explanation 1. **Understanding Radioactive Emissions**: - Radioactive materials can emit different types of radiation, primarily alpha particles, beta particles, and gamma rays. Each type of radiation has distinct properties. 2. **Types of Radiation**: - **Alpha Particles**: These are positively charged particles (helium nuclei) and are relatively heavy. They are not deflected by electric or magnetic fields due to their charge and mass. - **Beta Particles**: These are high-energy, high-speed electrons (or positrons) emitted from a nucleus during radioactive decay. Beta particles are negatively charged (electrons) or positively charged (positrons) and can be deflected by both electric and magnetic fields due to their charge. - **Gamma Rays**: These are electromagnetic waves (photons) and have no charge or mass. They are not deflected by electric or magnetic fields. - **X-Rays**: Similar to gamma rays, x-rays are also electromagnetic radiation and are not deflected by electric or magnetic fields. - **Ultraviolet Rays**: These are also electromagnetic waves and share the same properties as gamma rays and x-rays regarding deflection. 3. **Why Beta Rays are Correct**: - Since beta rays are charged particles, they will experience a force when placed in electric and magnetic fields. This force causes them to be deflected, which is a key characteristic of beta radiation. The deflection can be explained using the Lorentz force law, which states that a charged particle moving through a magnetic field experiences a force perpendicular to both its velocity and the magnetic field direction. 4. **Why Other Options are Incorrect**: - **B. Gamma Rays**: As mentioned, gamma rays are neutral and do not have mass. They do not interact with electric or magnetic fields, so they cannot be deflected. - **C. X-Rays**: Like gamma rays, x-rays are also neutral electromagnetic radiation and will not be deflected by electric or magnetic fields. - **D. Ultra-Violet Rays**: These rays are also electromagnetic radiation and share the same properties as gamma rays and x-rays, meaning they will not be deflected by electric or magnetic fields. ### Summary of Key Points - **Beta rays** are charged particles (electrons or positrons) and can be deflected by electric and magnetic fields. - **Alpha particles** are heavy and positively charged but are not deflected by these fields. - **Gamma rays**, **x-rays**, and **ultraviolet rays** are all neutral electromagnetic radiation and do not experience deflection in electric or magnetic fields. - Understanding the properties of different types of radiation is crucial for identifying their behavior in various fields. ### Revision Summary - Beta rays are charged and deflected by electric and magnetic fields. - Alpha particles are not deflected due to their mass and charge. - Gamma rays, x-rays, and ultraviolet rays are neutral and not deflected. - Familiarity with the characteristics of each type of radiation is essential for understanding their interactions.