Lecture 9 Review

Two point charges are located on the x-axis as follows: charge Q1 = +8x10-9C is at x = 0 cm and charge Q2 = -1x10-9C is at x = 1 cm. What is the net force in the x direction on a third charge, Q3 = +2x10-9C, placed at x = 2 cm ?

3.Three charges are placed on corners of an equilateral triangle as shown in Figure 1. An electron is placed at the center of the triangle. What is the magnitude of the net force on the electron? What is the direction of the net force on the electron?

3. In a hydrogen atom an electron circles a proton 3.In a hydrogen atom an electron circles a proton. Since the mass of the proton is much greater than the mass an electron, assume that the proton stays fixed in space and the electron rotates around it with radius 0.529x10-10 m. What is the velocity of the electron?

4.A uniform electric field exists in the region between two oppositely charged plane parallel plates. An electron is released from rest at the surface of the negatively charged plate and strikes the surface of the opposite plate 2x10-8 s later. If the magnitude of the electric field is 4x103 N/C, what is the separation between the plates?

5.Two charged particles are placed on the x-axis as follows: Q1 = 1x10-9 C at x = 0 m and Q2 = -2x10-9 C at x = 1.6 m. Where on the x axis is the electric field zero?

6.A conducting sphere is enclosed by two different conducting shells as shown in Fig. 4. The charge on the sphere is 1C. The charge on the inside surface of the outer most shell is -1C. What is the net charge on the middle shell?

7.Two stationary point charges are arranged on the x-axis as follows: Q1 = 2.4x10-10 C at x = 0 m and Q2 = -1.2x10-10 C at x = 1 m. An electron is placed at x = 2 m and let go. What is the velocity of the electron when it reaches x = 3 m.

8.Two point charges are located on the x-axis as follows: charge Q1 = +2x10-6C is at x = 0 m and charge Q2 = -1x10-6C is at x = 1 m. What is the net force in the x direction on a third charge, Q3 = -3x10-6C, placed at x = 2 m ?

9.Using the superposition principle determine the electric field at point P in Fig.4.

10. A 1 Coulomb charge is located at the origin 10.A 1 Coulomb charge is located at the origin. Another charge, Q, is located at x = 3 m. If the electric field is zero at x = 1 m, what is Q?

11. a. Five charges are arranged in a pentagon as shown in Fig. 6 11.a. Five charges are arranged in a pentagon as shown in Fig. 6. What is the direction of the net electric field at the center of the pentagon? b.What is the electrical potential (voltage) at the center of the pentagon?

12. An electron initially has velocity 5 x 105 m/s 12.An electron initially has velocity 5 x 105 m/s. It is accelerated through a potential of 2 V. What is its final velocity?

13. A conducting shell encloses a conducting sphere as shown in Fig. 5 13.A conducting shell encloses a conducting sphere as shown in Fig. 5. If the charge on the sphere is 3C and the charge on the outer surface of the conducting shell is -2C, what is the charge on the inner surface of the conducting shell?

14. A charge of -1x10-8C weighs 1 g 14.A charge of -1x10-8C weighs 1 g. It is released at rest from point P and moves to point Q. It's velocity at point Q is 1 cm/s. What is the potential difference, VP - VQ?