8.A water droplet of mass 3.00 x 10-12 kg is located in the air near the ground during a stormy day. An atmospheric electric field of magnitude 6.00 x 103 N/C points vertically downward in the vicinity of the water droplet. The droplet remains suspended at rest in the air.  What is the electric charge on the droplet?

A 2.6 mm -diameter sphere is charged to -4.5 nC . An electron fired directly at the sphere from far away comes to within 0.38 mm of the surface of the target before being reflected. a)What was the electron's initial speed? b)At what distance from the surface of the sphere is the electron's speed half of its initial value? c)What is the acceleration of the electron at its turning point?

32. Humid air breaks down (its molecules become ionized) in an electric field of 3.0 × 10° N/C. In that field, what is the magnitude of the electrostatic force on (a) an electron and (b) an ion with a single electron missing?

1. An electron moves along the x direction with a velocity of 1.2 x 107 m/s into an electric field -2800 N/C Ĵ. Determine how far in the y direction the electron is deflected in the time it takes to move 33 mm in the x direction if... a) The electric field is a constant -2800 N/C Ĵ. b) The electric field varies as -2800 sin(w t) where w = 109 s¹ and the particle enters the field at t = 0. Answers: a) 1.5 mm b) Forthcoming

4) A small plastic ball is suspended by a 0.30 m long thread in a uniform, horizontal electric field as shown in the figure. An electric field of 1,000 V/m is directed toward the right. The ball has a mass of 2.0x10 kg. If the ball is in equilibrium when the string makes an angle of 12° with the vertical as shown, what is the net charge on the ball? Clearly draw and label all forces and show how you arrive at your result. 0 E-1.00 x 10' N/C L He tot par m

CQ3: A proton moves through a uniform electric field of magnitude 7.0 N/C. The arrows below point in the direction of the electric field. The path of the charge is shown in blue. Ē = 7(-ĵ)N/C P 3 AVEO 1.9 m 45° P2 450 1.6 m Which of the following is the correct expression for AV? 450 AX11 11 AKI A) AV = -(7N/C)(1.9m) cos(45°) B) AV = −e(7N/C)(1.9m)cos(45°) c) AV = −(7N/C)(1.9m)–(7N/C)(1.6m) D) AV = −e(7N / C)(1.9m) – e(7N/C)(1.6m) E) AV = -(7N/C)(1.9m) cos(45°)-(7N/C)(1.6m) 26 AX AV=- E• AX₁1 - 9

In Rutherford's famous scattering experiments (which led to the planetary model of the atom), alpha particles (having charges of +2e and masses of 6.64 x 10-27 kg) were fired toward a fixed gold nucleus with charge +79e. An alpha particle, initially very far from the gold nucleus, is fired at 1.6 x 107 m/s directly toward the gold nucleus, as in Figure P16.19. How close does the alpha particle get to the gold nucleus before turning around? Ze Figure P16.19

3. In the front end of a Cathode Ray Tube (CRT) arrangement, an electron is fired toward a computer screen. It enters midway between two parallel plates with an initial speed of 6.15 x 10 m/s and its vertical deflection when it finally leaves the plates is 4.7 mm. Find the magnitude of the electric field between the plates. 1.0 cm d- 4.70 mm 10 cm 69.75

6. There is a point charge, q₁ = -5.00 nC, located at (0.800 m, 1.00 m) and a second point charge, 92 = +7.00 nC, located at (0.800 m, 0.00 m). What is the magnitude and direction of the net electric field at the origin as a result of the presence of these two charges. Y (0.800 m, 1.00 m) 91 (0.800 m,0.00 m) 92 X

Problem 7 An electron is placed in a uniform electric field of 0.15 N/C. Assume that the velocity of the electron is zero at t= 0. What is the velocity of the electron at t = 1 milliseconds? A) 5.3 × 10^7 m/s B) 8.8× 10^6 m/s C) 5.2× 10^7 m/s D) 2.6 × 10^7m/sE) 7.6 × 10^7 m/s