# Cathode Rays & Velocity: Uniform or Accelerated?

• mysteriously
In summary, the cathode rays are emitted from the cathode at very low pressure and it is said that they move at very high velocity if we apply a high potential difference between the electrodes. This velocity can be calculated using the equation v=sq.rt(2*p.d.*e/m).

#### mysteriously

During discharge tube experiment, the cathode rays are emitted from cathode at very low pressure...it is said that these rays move at very high velocity(if we apply high Potential Difference between 2 electrodes)...do these rays( stream of electrons) travel in uniform velocity or aren't they accelerated due to presence of external electric field?why do we directly find out the velocity of electron by the formula v=sq.rt(2*p.d.*e/m) ? i am confused whether the velocity of electrons is uniform or it is being accelerated by the external electric field??

mysteriously said:
During discharge tube experiment, the cathode rays are emitted from cathode at very low pressure...it is said that these rays move at very high velocity(if we apply high Potential Difference between 2 electrodes)...do these rays( stream of electrons) travel in uniform velocity or aren't they accelerated due to presence of external electric field?why do we directly find out the velocity of electron by the formula v=sq.rt(2*p.d.*e/m) ? i am confused whether the velocity of electrons is uniform or it is being accelerated by the external electric field??

While the electrons are emitted with some velocity, the overwhelming majority of the energy/speed picked up by the electrons are from the applied field. Remember, these are electrons! They are charged particles. Charged particles can interact with an external electric field. So you apply such a field to cause them to speed up.

If you apply a potential difference of V, then the energy gained by the electrons is eV = 1/2 mv^2 (assuming non-relativistic). So calculate your speed from there (assuming it started with 0 or negligible speed, which is a valid assumption in most cases).

P.S. This is not a "Quantum Physics" topic and has been moved out of that forum.

Zz.

dont they accelerate in the electric field?every charged particle in electric field is accelerated...then what and at what time is the velocity we calculate from above formula??

mysteriously said:
dont they accelerate in the electric field?every charged particle in electric field is accelerated...then what and at what time is the velocity we calculate from above formula??
You have a tube with a cathode at one end. Where is the anode?

mysteriously said:
dont they accelerate in the electric field?every charged particle in electric field is accelerated...then what and at what time is the velocity we calculate from above formula??

This is utterly puzzling. What did you think I meant when I said that these charge particles interact with electric field?

And why can't you just calculate the velocity? I've given you everything you need already!

Zz.

## 1. What are cathode rays?

Cathode rays are streams of electrons that are emitted from the cathode (negative electrode) of a high-voltage electrical discharge tube.

## 2. Are cathode rays uniform or accelerated in velocity?

Cathode rays are accelerated in velocity. As they travel from the cathode to the anode (positive electrode), they gain kinetic energy and their velocity increases.

## 3. How are the velocity of cathode rays measured?

The velocity of cathode rays can be measured using a variety of methods, such as the deflection of the rays in an electric or magnetic field, or by calculating the ratio of charge to mass of the particles.

## 4. What is the significance of the velocity of cathode rays?

The velocity of cathode rays is important because it can provide information about the properties of electrons, such as their mass and charge. It also played a crucial role in the development of television and other electronic devices.

## 5. Can the velocity of cathode rays be controlled?

Yes, the velocity of cathode rays can be controlled by adjusting the voltage and electric/magnetic fields in the discharge tube. This allows for the manipulation and study of the properties of electrons.