CATHODE RAYS CAUSES AN OBJECT PLACED BEHIND A PERFORATED ANODE TO CAST A SHADOW ON THE SCREEN. THIS OBSERVATION SHOWS THAT THE RAYS

• A. are positively charged
• B. are negatively charged
• C. have mass
• D. travel in straight lines ✓

The answer to the question is: D. travel in straight lines

The observation that cathode rays cause an object placed behind a perforated anode to cast a shadow on the screen indicates that the rays travel in straight lines. This phenomenon is a fundamental characteristic of cathode rays and is a key aspect of their behavior. When cathode rays are emitted from the cathode and pass through the perforated anode, they create a shadow of the object placed behind it, demonstrating that they travel in straight lines.

Cathode rays are streams of electrons that are emitted from the cathode (negative electrode) in a vacuum tube. These rays were first observed by Sir William Crookes in 1879 and later studied extensively by J.J. Thomson, who determined that they were negatively charged particles with a very small mass. The behavior of cathode rays has been a subject of significant scientific inquiry and has contributed to our understanding of the nature of electrons and their properties.

The observation that cathode rays cause a shadow to be cast on a screen when passing through a perforated anode provides evidence that these rays travel in straight lines. This behavior is consistent with the characteristics of particles or rays traveling in a vacuum, as they are not subject to significant deflection or dispersion in the absence of external forces.