Skip to main content
Ch 21: Electric Charge and Electric Field
Chapter 21, Problem 12b

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\times10^{-15} m. What magnitude of electric field does it produce at the distance of the electrons, which is about 1.0×10101.0\times10^{-10} m?

Verified step by step guidance
1
First, recognize 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. This is due to Gauss's Law.
Calculate the total charge of the uranium nucleus. Since uranium has 92 protons, and each proton has a charge of approximately 1.6×10−19 C, the total charge Q is given by Q = 92 × 1.6×10−19 C.
Use the formula for the electric field E due to a point charge at a distance r: E = (1/(4πϵ₀)) × (Q/r²), where ϵ₀ is the permittivity of free space, approximately 8.85×10−12 C²/(N·m²).
Substitute the values into the formula: Q = 92 × 1.6×10−19 C and r = 1.0×10−10 m. Calculate the electric field E using these values.
Ensure the units are consistent and check the calculation for any errors. The result will give you the magnitude of the electric field at the distance of the electrons.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

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

Coulomb's Law

Coulomb's Law describes the force between two point charges. It states that the electric force between two charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. This principle is essential for calculating the electric field produced by a charged nucleus at a given distance.
Recommended video:
Guided course
09:52
Coulomb's Law

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). Understanding the electric field is crucial for determining the magnitude of the field produced by the uranium nucleus at the distance of the electrons.
Recommended video:
Guided course
03:16
Intro to Electric Fields

Spherical Charge Distribution

A spherical charge distribution assumes that the charge is uniformly distributed over the surface of a sphere. For a spherically symmetric charge distribution, the electric field outside the sphere can be calculated as if all the charge were concentrated at the center. This concept simplifies the calculation of the electric field at a distance from the nucleus.
Recommended video:
05:51
Refraction at Spherical Surfaces
Related Practice
Textbook Question

Two small plastic spheres are given positive electric charges. When they are 15.015.0 cm apart, the repulsive force between them has magnitude 0.2200.220 N. What is the charge on each sphere if the two charges are equal?

1166
views
Textbook Question

Two small plastic spheres are given positive electric charges. When they are 15.015.0 cm apart, the repulsive force between them has magnitude 0.2200.220 N. What is the charge on each sphere if one sphere has four times the charge of the other?

3109
views
Textbook Question

Suppose you had two small boxes, each containing 1.01.0 g of protons.

(a) If one were placed on the moon by an astronaut and the other were left on the earth, and if they were connected by a very light (and very long!) string, what would be the tension in the string? Express your answer in newtons and in pounds. Do you need to take into account the gravitational forces of the earth and moon on the protons? Why?

(b) What gravitational force would each box of protons exert on the other box?

871
views
Textbook Question

Three point charges are arranged on a line. Charge q3=+5.00q_3=+5.00 nC and is at the origin. Charge q2=3.00q_2=-3.00 nC and is at x=+4.00x = +4.00 cm. Charge q1q_1 is at x=+2.00x = +2.00 cm. What is q1q_1 (magnitude and sign) if the net force on q3q_3 is zero?

2801
views
Textbook Question

Three point charges are arranged along the xx-axis. Charge q1=+3.00q_1=+3.00 μ\muC is at the origin, and charge q2=5.00q_2=-5.00 μ\muC is at x=0.200x = 0.200 m. Charge q2=8.00q_2=-8.00 μ\muC. Where is q3q_3 located if the net force on q1q_1 is 7.007.00 N in the x-x-direction?

2576
views
Textbook Question

A positive charge qq is fixed at the point x=0x = 0, y=0y = 0, and a negative charge 2q-2q is fixed at the point x=ax = a, y=0 y = 0. Show the positions of the charges in a diagram.

1689
views