Question

In a cathode ray experiment, in the discharge tube $1$, hydrogen gas is taken in tube $2$ helium gas is taken will there be any difference in the $\dfrac{e}{m}$ value of anode rays?

Answer 1

In this question the gases hydrogen and helium are filled in the tubes, one needs to find out whether this will have any effect on the cathode ray experiment. As per the cathode ray experiment the electrons are negatively charged for a cathode ray. This approach can be applied to solve the question.

Complete step by step answer:
-In the cathode ray experiment, the cathode rays are the beam of electrons and they are negatively charged. These cathode-ray electrons are identical to each other.
-Therefore, the ratio of charge to mass $\left( {\dfrac{e}{m}} \right)$ of the cathode rays is similar for all the gases irrespective of their properties.
- But in the case of anode rays, they are positively charged species. Also, the anode rays are made up of ionized nuclei which change from gas to gas as in terms of their atomic number and their mass number.
-Therefore, in anode rays the charge to mass ratio $\left( {\dfrac{e}{m}} \right)$ of the positively charged ions changes as there is a change in the number of nucleons in the nucleus of each gas as per the different types of gas, making the change in the ratio for every different type of gas.
-Therefore, In the cathode ray experiment the discharge tube $1$ is filled with hydrogen gas and in tube $2$ helium gas is taken and there will not be any change/difference in the $\left( {\dfrac{e}{m}} \right)$ value in case of anode rays which is the answer.

Note: In the cathode ray experiment the cathode rays are negative charges hence, they don’t have any effect on them irrespective of the gas used in the tube. But In the case of anode rays which are positively charged and made from the ionized nuclei, they change their ratio as the gas changes. From this one should remember that cathode rays are negatively charged rays and they don’t change their $\left( {\dfrac{e}{m}} \right)$ value as the gas changes i.e. value is the same for all gases.