Question

1. In the Bohr model of the hydrogen atom, a single electron orbits a single proton at a distance r-0.50 x 10-10 meters as shown. a) b Assuming the Coulomb force supplies the necessary centripetal force, find the Find the value of the attractive Coulomb force exerted on the electron. electron's speed v in its orbit about the nucleus. Can a charged object exert forces on an uncharged object? If so, will this force be attractive, repulsive, or is either possible? Explain your reasoning 2. A stationary proton is released in a uniform electric field of 10,000 N/C as shown. Assuming the electrical force to be the only force acting on the proton (no gravity, air resistance, etc.), find the proton's speed after traveling a distance of 10.0 cm. Which direction will it travel, left or right? Hint: You may wish to review the kinematic equations in Ch. 2, page 56. 3. 4

Answer 1

Charge of proton e = 1.6 times 10^-19 C charge of electron q = -e = -1.6 times 10^-19 C Distance r = 0.5 times 10^-10 m Coulomb�s constant K = 8.99 times 10^9 N m^22/C^2 (a) Attractive force on electron F = K e q/r^2 F = (8.99 times 10^9) (1.6 times 10^-19) (1.6 times 10^-19)/(0.5 times 10^-10)^2 = 9.3 = 20576 times 10^-8 N (b) we know F = m V^2/r V^2 = F r/m where m = mass of electron = 9.11 times 10^-31 kg = (9.20576 times 10^-8) (0.5 times 10^-10)/(9.11 times 10^-31) = 5.052 times 10^12 V = 2.2477 times 10^6 m/s