Anode Rays: Dependence of e/m ratio on nature of gas


Anode rays are the positively charged ions produced when a high voltage is applied across a discharge tube filled with a gas at low pressure. These rays travel towards the cathode and are deflected by electric and magnetic fields.


Influence of Gas
The e/m ratio for anode rays depends on the nature of the gas used in the discharge tube. The e/m ratio is the charge-to-mass ratio of the positive ions. Different gases have different atomic and molecular structures, which affect the mass and charge distribution of the ions produced in the tube.

Gas Ionization
When high voltage is applied across the discharge tube, the gas atoms or molecules get ionized. The positively charged ions are accelerated towards the cathode, forming the anode rays. The e/m ratio is determined by measuring the deflection of these rays in an electric or magnetic field.

Gas Composition
The nature of the gas determines the composition of the positive ions produced. Different gases have different atomic or molecular masses and charge distributions. This affects the motion and deflection of the anode rays in electric and magnetic fields.

Mass and Charge Distribution
The mass of the positive ions depends on the atomic or molecular mass of the gas. Heavier gases will have larger masses for their positive ions, while lighter gases will have smaller masses. The charge distribution in the ions depends on the ionization process and the atomic or molecular structure of the gas.

Effect on e/m Ratio
Since the e/m ratio is the ratio of the charge to the mass of the ions, any change in the mass or charge distribution will affect this ratio. Therefore, the e/m ratio for anode rays varies with the nature of the gas used in the discharge tube.


Cathode rays are the negatively charged electrons produced when a high voltage is applied across a discharge tube filled with a gas at low pressure. Unlike anode rays, the e/m ratio for cathode rays remains constant regardless of the nature of the gas.

Reason for Constant e/m Ratio
The e/m ratio for cathode rays remains constant because electrons have a fixed mass and charge. Electrons are fundamental particles with a mass of 9.10938356 × 10⁻³¹ kilograms and a charge of -1.602176634 × 10⁻¹⁹ coulombs. These values do not depend on the nature of the gas used in the discharge tube.

Measurement of e/m Ratio
The e/m ratio for cathode rays can be measured using a variety of methods, such as the Thomson method or the deflecting electric field method. These methods involve applying electric and magnetic fields to the cathode rays and measuring their deflection. By knowing the values of the applied fields and the deflection, the e/m ratio can be calculated.

Conclusion
In conclusion, the e/m ratio for anode rays depends on the nature of the gas used in the discharge tube because different gases have different mass and charge distributions for their positive ions. On the other hand, the e/m ratio for cathode rays remains constant as electrons have a fixed mass and charge,