A simple and common technique for accelerating electrons is...

A simple and common technique for accelerating electrons is shown in Eigure 7.46. where there is a uniform electric field between two plates. Electrons are released, usually from a hot filament, near the negative plate, and there is a small hole in the positive plate that allows the electrons to continue moving. (a) Calculate the acceleration of the electron if the field strength is $2.50 \times 10^4 \mathrm{~N} / \mathrm{C}$. (b) Explain why the electron will not be pulled back to the positive plate once it moves through the hole. FIGURE CANT COPY Figure 7.46 Parallel conducting plates with opposite charges on them create a relatively uniform electric field used to accelerate electrons to the right. Those that go through the hole can be used to make a TV or computer screen glow or to produce $\mathrm{X}$ - rays.

A simple and common technique for accelerating electrons is shown in Eigure 7.46. where there is a uniform electric field between two plates. Electrons are released, usually from a hot filament, near the negative plate, and there is a small hole in the positive plate that allows the electrons to continue moving. (a) Calculate the acceleration of the electron if the field strength is $2.50 \times 10^4 \mathrm{~N} / \mathrm{C}$. (b) Explain why the electron will not be pulled back to the positive plate once it moves through the hole.
FIGURE CANT COPY
Figure 7.46 Parallel conducting plates with opposite charges on them create a relatively uniform electric field used to accelerate electrons to the right. Those that go through the hole can be used to make a TV or computer screen glow or to produce $\mathrm{X}$ - rays.

Key Concepts

Electric Field

An electric field is a region in which a charged particle experiences a force proportional to its charge. In many physical systems, such as between parallel plates, a uniform electric field is employed to ensure that the force on a charged particle remains constant, allowing for predictable acceleration according to the relation F = qE.

Newton's Second Law for Charged Particles

Newton's second law, F = ma, applies to charged particles by combining it with the force due to an electric field (F = qE). This leads to the acceleration of a charged particle being given by a = qE/m, which is fundamental when calculating the motion of electrons and other charged particles in an electric field.

Uniform Electric Fields Between Parallel Plates

Using parallel plates to create a uniform electric field is a common technique in various applications, from cathode ray tubes to particle accelerators. The uniformity of the field ensures that the charged particles experience a constant force and thereby achieve uniform acceleration, making it easier to control their paths and energies.

Electric Potential and Field Boundaries

Electric potential relates to the work done on a charged particle by an electric field; in systems with designated boundaries, such as a hole in the plate, once a charged particle passes through the region of a strong, defined field, it may no longer experience a significant opposing force. This means that the particle, having gained kinetic energy, continues on its trajectory without being pulled back by the field.

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