Question

which is not true with respect to cathode rays:
(A) Cathode rays consist of fast moving electrons.
(B) For production of cathode rays in a discharge tube,the gas filled should be at a low pressure
(C) For production of cathode rays in a discharge tube,the voltage applied across the electrodes should be high.
(D) None of these.​

Answer 1

Answer:

• (D)None of these.

EXPLANATION:

• Because all the other options are true.
• Cathod ray consists of fast moving electrons because cathod ray is made up negatively charge particals called electrons.
• At low pressure ($10^{-2}$ atm) and higher voltage (10000 V) gases are partially ionised in the discharge tube. Positive ions of gases strike on the cathode. Due to the thermal effect, a beam of electrons releases from the surface of the cathode. This is called a cathode ray.
• When a high voltage is applied to the tube the electric field accelerates the small number of electrically charged ions always present in the gas created by natural phenomena called photo-ionization and radioactivity.

May this help you much.