Question

When the electric field is applied, the cathode rays bend towards :
A. negative plate
B. positive plate
C. will remain unaffected in an electric field
D. can not predict

Answer 1

Cathode rays (also known as electron beams or e-beams) are electron streams observed in vacuum tubes. When a voltage is applied to an evacuated glass tube with two electrodes, the glass opposite the negative electrode glows from electrons emitted by the cathode. Electrons were first discovered as cathode ray constituents.

Complete answer:
Cathode rays get their name from the negative electrode, or cathode, in a vacuum tube. To get electrons into the tube, they must first be separated from the cathode atoms. Crookes tubes, the first cold cathode vacuum tubes, used a high electrical potential between the anode and the cathode to ionize the residual gas in the tube.

The electric field accelerated the ions and the ions released electrons when they collided with the cathode. When a cathode ray passes through this electric field, the negatively charged electrons are deflected away from the negatively charged plate and toward the positively charged plate.

Electrons were first discovered as cathode ray constituents. To arrive at this conclusion, many small but critical experimental steps were required, such as determining whether cathode rays travel in straight lines, carry energy, or, as explored in this tutorial, are affected by magnetic fields. So, Cathode rays are a stream of negatively charged particles that bend towards the positive plate in an electric field.

Thus, the answer is option B.

Note: Cathode rays are invisible, but their presence was first detected in early vacuum tubes when they struck the glass wall, exciting the glass atoms and causing them to emit light—a glow known as fluorescence. Researchers noticed that objects placed in the tube in front of the cathode could cast shadows on the glowing wall and concluded that something must be traveling in straight lines from the cathode. After reaching the anode, electrons travel through the anode wire to the power supply and back to the cathode, resulting in cathode rays carrying electric current through the tube.