Problem 21.
Three small spheres are enclosed in surface carrying charges q1 = 4 nC, q2 = 10.00 nC, and q3 = 5 nC.
Surface (s) What it encloses
s1 q1
s2 q2
s3 q1 and q2
s4 q1 and q3
s5 q1, q2 and q3
Find the net electric flux through each of the following closed surfaces.
(a) s1
(b) s2
(c) s3
(d) s4
(e) s5
Solution
Problem 22.
Two plastic spheres, each carrying charge uniformly distributed throughout its interior, are initially placed in contact and then released. The first sphere has a diameter of 60 cm, a mass of 50 g, and contains of charge. The second sphere has a diameter of 40 cm, a mass of 150 g and contains of charge. Assume that no other forces are acting on them.
(a) Find the maximum speed achieved by the first sphere.
(b) Find the maximum acceleration achieved by the first sphere.
Solution
Problem 23.
A particle with a charge of +8 nC is in a uniform electric field E directed to the left. It is released from rest and moves to the left. After it has moved 3 cm, its kinetic energy is found to be
(a) What work was done by the electric force?
(b) What is the potential of the starting point with respect to the endpoint?
(c) What is the magnitude of E?
Solution
Problem 24.
A total electric charge of 8 nC is distributed uniformly over the surface of a metal sphere with a radius of 27 cm. If the potential is zero at a point at infinity, find the value of the potential at the following distances from the center of the sphere.
(a) 52 cm
(b) 20 cm
(c) 9 cm
Solution
Problem 25.
A potential difference of 10 kV is established between parallel plates in air.
(a) If the air becomes electrically conducting when the electric field exceeds , what is the minimum separation of the plates?
(b) When the separation has the minimum value calculated in part (a), what is the surface charge density on each plate?
Solution
Problem 26.
An alpha particle with kinetic energy 10 MeV makes a headon collision with a lead nucleus at rest. What is the distance of closest approach of the two particles? (Assume that the lead nucleus remains stationary and that it may be treated as a point charge. The atomic number of lead is 82. The alpha particle is a helium nucleus, with atomic number 2.)
Solution
Problem 27.
In a certain region of space, the electric potential is is , , where A, B, and C are positive constants.
(a) Calculate the x, y, and zcomponents of the electric field.
(b) At which points is the electric field equal to zero?
Solution
Problem 28.
A point charge is held stationary at the origin. A second point charge is moves from the point x = 0.20 m, y = 0 to the point x = 0.3 m, y = 0.35 m. How much work is done by the electric force on ?
Solution
Problem 29.
A parallelplate air capacitor has a capacitance of 800 pF. The charge on each plate is 6 µC. What is the potential difference between the plates?
Solution
Problem 30.
A parallelplate air capacitor of capacitance of 100 pF has a charge of magnitude 0.1 µC on each plate. The plates are 0.5 mm apart.
(a) What is the potential difference between the plates?
(b) What is the area of each plate?
(c) What is the electricfield magnitude between the plates?
(d) What is the surface charge density on each plate?
Solution
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