refatronic.blogg.se - Who did the cathode ray experiment

In 1932, Chadwik discovered neutron by bombarding a thin sheet of beryllium by α-particles.The eminent physicist Johann Hittorf discovered cathode rays in 1869 in Crookes tubes.

The smallest and lightest positive ion was obtained from hydrogen and was called proton.

The behavior of positively charged particles in magnetic or electrical field is opposite to that observed for electrons.

Some of the positively charged particles carry a multiple of the fundamental unit of electrical charge.

The charge to mass ratio of particles depends on the gas from which they originate.

These are simply the positively charged gaseous ions.

Mass of positively charged particles depends upon the nature of gas present in cathode ray tube.

The characteristics of positively charged particles are as follows: These rays carry positively charged particles. The mass of electron was determined by combining these results with Thomson’s value of e/m e ratio The present accepted value of electrical charge is -1.602176 × 10 -19 C According to Millikan, charge on electron is -1.6 × 10 -19 C. Charge on ElectronĪ Millikan devised the oil drop experiment (1906-14) to determine the charge on electron. As electrons are negatively charged, the charge on electron is –e.

Here, m e is mass of electron in kg and e is the magnitude of charge on electron in coulomb (C). In other words, deflection increases with increase in strength of magnetic field.īased on his observations, Thomson gave the value of ratio of charge to mass as follows: Deflection of electrons from original path increases with increase in voltage.The mass of the particle: lighter the particle, greater the deflection.When charge on the particle is greater interaction with electric or magnetic field is greater and so there is greater deflection. The magnitude of the negative charge on the particle.According to Thomson, the amount of deviation of particles from their path in the presence of electrical or magnetic field depends upon following: He applied electrical and magnetic field perpendicular to each other and also to the path of electrons. Thomson measured the ratio of electrical charge (e) to the mass of electron (m e) by using cathode ray tube. Thus, it was concluded that electrons are basic constituent of all the atoms. The characteristics of cathode rays do not depend upon the material of electrodes or on the nature of gas present in cathode ray tube.This suggests that cathode rays consist of negatively charged particles, viz. When either electrical or magnetic field is present, cathode rays behave as negatively charged particles.When there is no electrical or magnetic field, these rays travel in straight lines.These rays are not visible but their behavior can be observed with the help of fluorescent materials because such materials glow when hit by cathode rays.Cathode rays move from cathode to anode.When these rays (after passing through anode) hit the coating, a bright spot is formed on the coating. The flow of current was further checked by making a hole in the anode, and coating the tube (behind anode) with phosphorescent material zinc sulphide. These particles are called cathode rays or cathode ray particles. These particles move from the negative electrode (cathode) to the positive electrode (anode). When enough high voltage is applied across the electrodes, current starts to flow through a stream of particles. Evacuation of glass tube helps in manipulating the pressure of different gases in the tube. The electrical discharge through the gases can only be observed at very low pressure and at very high voltage. It contains two thin pieces of metal which are called electrodes, sealed inside.

Structure of Cathode Ray Tube: This tube is made of glass.