(a) What are the cathode rays? What is the nature of charge on cathode rays?
(b) Explain how cathode rays are formed from the gas taken in the discharge tube.
(c) What conclusion is obtained from the fact that all the gases form cathode rays?
(a) What are the cathode rays? What is the nature of charge on cathode rays?
(b) Explain how cathode rays are formed from the gas taken in the discharge tube.
(c) What conclusion is obtained from the fact that all the gases form cathode rays?
(a) A cathode ray is a beam of electrons in a vacuum tube traveling from the negatively charged electrode (cathode) at one end to the positively charged electrode (anode) at the other, across a voltage difference between the electrodes. They are also called electron beams.
Cathode rays consist of negatively charged particles called electrons. So the nature of charge possessed by particles of cathode rays is negative.
(b) Cathode rays are emitted by the cathode in a vacuum tube and this is done by using Crookes tube or now modem vacuum tubes (or discharge tubes).
The high electric potential is applied between the anode and cathode to ionize the residual gas in the tube. The ions are accelerated by electric field and they collided with cathode which released electrons. As electrons are negatively charged they are repelled by the cathode and are attracted towards the anode. Electrons travel in a straight line in the empty tube. They have high velocities and are colourless (invisible).
(c) The existence of electrons in an atom was shown by J.J. Thomson in 1897. Thomson passed electricity at high voltage through a gas at very low pressure taken in a discharge tube. Streams of minute particles were given out by the cathode (negative electrode). These streams of particles are called cathode rays (because they come out of cathode). The mass and charge of the cathode ray particles do not depend on the nature of gas taken in the discharge tube. Cathode rays consist of small, negatively charged particles called electrons. Since all the gases form cathode rays, it was concluded that all the atoms contain negatively charged particles called electrons.
(a) A cathode ray is a beam of electrons in a vacuum tube traveling from the negatively charged electrode (cathode) at one end to the positively charged electrode (anode) at the other, across a voltage difference between the electrodes. They are also called electron beams.
Cathode rays consist of negatively charged particles called electrons. So the nature of charge possessed by particles of cathode rays is negative.
(b) Cathode rays are emitted by the cathode in a vacuum tube and this is done by using Crookes tube or now modem vacuum tubes (or discharge tubes).
The high electric potential is applied between the anode and cathode to ionize the residual gas in the tube. The ions are accelerated by electric field and they collided with cathode which released electrons. As electrons are negatively charged they are repelled by the cathode and are attracted towards the anode. Electrons travel in a straight line in the empty tube. They have high velocities and are colourless (invisible).
(c) The existence of electrons in an atom was shown by J.J. Thomson in 1897. Thomson passed electricity at high voltage through a gas at very low pressure taken in a discharge tube. Streams of minute particles were given out by the cathode (negative electrode). These streams of particles are called cathode rays (because they come out of cathode). The mass and charge of the cathode ray particles do not depend on the nature of gas taken in the discharge tube. Cathode rays consist of small, negatively charged particles called electrons. Since all the gases form cathode rays, it was concluded that all the atoms contain negatively charged particles called electrons.
