# Charge and Current AS Question

• coolnufc
In summary, the beam current in a television tube is 32mA and the electrons travel at a speed of 4.2x10^7m/s through a distance of 21cm. The number of electrons striking the screen in 1 hour is 7.2x10^20 and the number of electrons in the beam at any instant is 3.2x10^-5 * 6.241x10^18 * 0.21/4.2x10^7.
coolnufc
The beam current in a television tube is 32mA. The electrons travel at a speed of 4.2x10^7m/s through a distance 21cm.

a) The number of electrons striking the screen in 1 hour is?

I did: Q=IT = 0.032A x (60x60)s = 115.2 C

Number of electrons = 115.2/1.6x10^-19 = 7.2x10^20

b) The number of electrons in the beam at any instant is?

I tried doing the same as above but for one seconds but couldn't work it out at all. Anyone give me a clue?

The length of your beam is .21 m.

In 1 sec you would have a beam column containing of .032ma.

A 1 sec column would contain 3.2*10-5*6.241*1018 electrons of which only .21/4.2*107 are actually in motion within the tube.

To calculate the number of electrons in the beam at any instant, you would need to know the cross-sectional area of the beam. This would allow you to calculate the volume of the beam and then use the speed of the electrons to determine the number of electrons passing through that volume in one second. However, without this information, it is not possible to accurately determine the number of electrons in the beam at any instant.

## What is charge?

Charge is a fundamental property of matter that determines how objects interact with electromagnetic fields. It can be either positive or negative, and is measured in units of Coulombs (C).

## What is current?

Current is the rate of flow of electric charge. It is measured in units of Amperes (A) and is the amount of charge that passes through a given point in a conductor per unit time.

## What is the relationship between charge and current?

Charge and current are closely related, as current is the movement of electric charge. In other words, current is the change in charge over time. This relationship is described by Ohm's Law: I = Q/t, where I is current, Q is charge, and t is time.

## What are some examples of objects with high charge?

Objects with high charge include lightning bolts, van de Graaff generators, and charged balloons. These objects have an excess or deficit of electrons, resulting in a large amount of charge.

## How does current flow in a circuit?

In a circuit, current flows from the positive terminal of a battery or power source, through the wires and components, and back to the negative terminal. This flow is made possible by the movement of electrons, which are negatively charged particles.

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