# Why do cathode rays move in a straight line ?

Cathode rays move in a straight line primarily due to their nature as charged particles, specifically electrons, emitted from a cathode in a vacuum tube. When electrons are emitted from the cathode, they possess kinetic energy and are influenced by the electric potential difference within the tube. In the absence of any external forces like electric or magnetic fields, the electrons travel along straight paths due to their inertia and the absence of deflecting forces. This straight-line trajectory is a result of the initial direction imparted to the electrons by the emission process and their tendency to continue in motion unless acted upon by an external force.

Electrons, which constitute cathode rays, travel in straight lines because of their inertia and the absence of significant external forces to alter their trajectory. In a vacuum or low-pressure environment, where the mean free path (the distance an electron can travel before colliding with another particle) is long, electrons emitted from the cathode move freely until they encounter an obstacle or interact with another particle. This movement in a straight line is consistent with the principles of Newtonian mechanics, where an object in motion remains in motion unless acted upon by an external force.

Cathode rays, consisting of electrons, do travel in straight lines and possess momentum. The momentum of an electron is determined by its mass and velocity, and since cathode rays are streams of electrons moving at high velocities, they carry momentum. In the absence of external forces, such as electric or magnetic fields, which could deflect or accelerate them, cathode rays maintain their straight-line trajectory based on their initial emission direction and velocity. The momentum of cathode rays is a crucial factor in understanding their behavior in various applications, including electron microscopy and cathode ray tubes.

Yes, cathode rays travel in straight lines even in the absence of electric or magnetic fields. Once electrons are emitted from the cathode, they continue along straight paths unless influenced by collisions with other particles or external forces. In a vacuum or low-pressure environment, where interactions with other particles are minimal, cathode rays maintain their straight-line trajectory due to their kinetic energy and the absence of deflecting forces. This straight-line motion is a fundamental characteristic of cathode rays and plays a significant role in their application in electron beam technologies and scientific experiments.