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Ch 22: Gauss' Law
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
Chapter 22, Problem 12a

The nuclei of large atoms, such as uranium, with 9292 protons, can be modeled as spherically symmetric spheres of charge. The radius of the uranium nucleus is approximately 7.4×10157.4\(\times\)10^{-15} m. What is the electric field this nucleus produces just outside its surface?

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Understand that the electric field produced by a spherically symmetric charge distribution outside the sphere can be treated as if all the charge were concentrated at the center of the sphere. This is due to Gauss's Law.
Calculate the total charge of the uranium nucleus. Since uranium has 92 protons, the charge can be calculated using the formula: Q=92×e, where e is the elementary charge, approximately 1.6×10^-19C.
Apply Gauss's Law to find the electric field just outside the surface of the nucleus. Gauss's Law states: E×A=Qε0, where E is the electric field, A is the surface area of the sphere, and ε0 is the permittivity of free space, approximately 8.85×10^-12C/N·m^2.
Calculate the surface area of the sphere using the formula: A=4πr^2, where r is the radius of the nucleus, given as 7.4×10^-15m.
Substitute the values of Q, A, and ε0 into Gauss's Law to solve for the electric field E just outside the surface of the uranium nucleus.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electric Field

The electric field is a vector field around a charged object where a force would be exerted on other charges. It is defined as the force per unit charge and is measured in newtons per coulomb (N/C). For a spherically symmetric charge distribution, the electric field just outside the surface can be calculated using Gauss's Law.
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Intro to Electric Fields

Gauss's Law

Gauss's Law relates the electric flux through a closed surface to the charge enclosed by that surface. It states that the total electric flux is equal to the enclosed charge divided by the permittivity of free space. For a spherical charge distribution, this simplifies the calculation of the electric field outside the surface.
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Spherically Symmetric Charge Distribution

A spherically symmetric charge distribution means the charge is uniformly distributed over a spherical volume. This symmetry allows simplification in calculating the electric field, as the field at any point outside the sphere depends only on the total charge and the distance from the center, not the specific distribution within the sphere.
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Related Practice
Textbook Question

The nuclei of large atoms, such as uranium, with 9292 protons, can be modeled as spherically symmetric spheres of charge. The radius of the uranium nucleus is approximately 7.4×10157.4\(\times\)10^{-15} m. The electrons can be modeled as forming a uniform shell of negative charge. What net electric field do they produce at the location of the nucleus?

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Textbook Question

Some planetary scientists have suggested that the planet Mars has an electric field somewhat similar to that of the earth, producing a net electric flux of 3.63×1016-3.63\(\times\)10^{16} Nm2/C at the planet's surface. Calculate the electric field at the planet's surface (refer to the astronomical data inside the back cover).

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Textbook Question

A hemispherical surface with radius rr in a region of uniform electric field E\(\overrightarrow{E}\) has its axis aligned parallel to the direction of the field. Calculate the flux through the surface.

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Textbook Question

A charged paint is spread in a very thin uniform layer over the surface of a plastic sphere of diameter 12.012.0 cm, giving it a charge of 49.0−49.0 μμC. Find the electric field just outside the paint layer;

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Textbook Question

Some planetary scientists have suggested that the planet Mars has an electric field somewhat similar to that of the earth, producing a net electric flux of 3.63×1016-3.63\(\times\)10^{16} Nm2/C at the planet's surface. Calculate the total electric charge on the planet.

2
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Textbook Question

A charged paint is spread in a very thin uniform layer over the surface of a plastic sphere of diameter 12.012.0 cm, giving it a charge of 49.0−49.0 μμC. Find the electric field just inside the paint layer.

2
views