Question

Electrons in a cathode ray tube have been emitted with a velocity of $1000\, m s ^{-1}$. The number of following statements which is/are true about the emitted radiation is _______
Given : $h =6 \times 10^{-34} J s , m _e=9 \times 10^{-31} kg$.
(A) The deBroglie wavelength of the electron emitted is $666.67 \,nm$.
(B) The characteristic of electrons emitted depend upon the material of the electrodes of the cathode ray tube.
(C) The cathode rays start from cathode and move towards anode.
(D) The nature of the emitted electrons depends on the nature of the gas present in cathode ray tube.

Answer 1

(A) $V _{ c }=1000 \,m / s ; h =6 \times 10^{-34} \,Js$;
$m _{ e }=9 \times 10^{-31} kg$
$\lambda=\frac{ h }{ mv }=\frac{6 \times 10^{-34}}{9 \times 10^{-31} \times 1000}=666.67 \times 10^{-9} \,m$
$=666.67 \,nm$
(B) The characteristic of electrons emitted is independent of the material of the electrodes of the cathode ray tube.
(C) The cathode rays start from cathode and move towards anode.
(D) The nature of the emitted electrons is independent on the nature of the gas present in cathode ray tube.