Question

Cathode rays are produced when high voltage is applied across a gas under:

• A. high pressure
• B. low pressure $(\approx 0.1torr)$
• C. very low pressure $\left({10}^{-3}torr\right)$
• D. ordinary pressure

Answer 1

The correct option is C very low pressure $\left({10}^{-3}torr\right)$

Cathode ray is the flow of electrons observed in vacuum tubes. An evacuated glass tube is equipped with two electrodes and a voltage is applied at very low pressure(${10}^{-3}$ torr) the glass opposite to the negative electrode is observed to glow. So the correct option is C