Question

Among the following, the correct statement about cathode ray discharge tube is:
A. The electrical discharge can only be observed at high pressure and at low pressure and low voltage
B. In the absence of external electrical or magnetic field, cathode rays travel in the straight line
C. The characteristics of cathode rays depend upon the material of electrodes
D. The characteristics of cathode rays depend upon the gas present in the cathode ray tube

Answer 1

Hint: Cathode rays are E.M. waves. They are positive particles. The magnitude for charge and mass is the same, irrespective of the gas. The characteristic of the cathode ray remains constant in every tube. We will use the characteristics to eliminate the possible answers. So, we need to analyse the the option to check out the correct statement.

Complete answer:
Michael Faraday a scientist begun study of electrical discharge in vacuum tubes known as cathode ray discharge tubes.

Cathode rays are independent of the gas and the material used to make the tube. All the gases have the same value for charge to mass ratio. It is majorly observed in electrical and magnetic fields.
These Cathodes travel in a straight-line path irrespective of external magnetic or electrical field. The direction can change but not the alignment.

Cathode rays originate from the cathode and go towards the anode since they are positive in charge. The use of cathode ray tubes in T.V for producing fluorescence of the back of the telly screen. The principle of the discharged tube, in application, used to create fluorescent lamps, neon lamps. Also, the same principle is used in a CRT old-fashioned television.

So, the correct answer is Option B.

Note: Electrical discharge carried out in vacuum tubes lead to the discovery of canal rays which have positively charged particles. Their properties is different from the electron and cathode rays in the electrical and magnetic field. The Cathode ray tube experiment uses fluorescent material to emit light. This experiment is based on the principle is of excitation and de excitation of electrons. When an electron is excited to a higher energy level, it falls back to ground state while emitting different energy in the form of light.