Assignment 7DO NOT WRITE on THIS PAPER
Assignment 7DO NOT WRITE ON THIS PAPER!!
1. The diagram below is of a hydrogen atom.
a) Label the proton in the nucleus with a positive sign and the orbitalelectron with a negative sign.
b) The electrical interaction between the nucleus and the electron is aforce of (attraction, repulsion).
2. The outer electrons in metals are not tightly bound to the atomic nuclei. They are free to roam in the material. Such materials are good _____.
3. How many electrons are in 1.92 x 10–18 C?
4. By convention, what is the charge of
a) Electronsb) Protonsc) Neutrons?
5. Like charges ____ and opposite charges ____.
6. What is the principle of conservation of charge?
7. The ______of many atoms are bound very loosely to an atom and can be easily dislodged.
a) Outermost electrons
b) Innermost electrons
c) Outermost protons
d) Innermost protons
8. A charged atom is called a(n) ______.
9. Define semiconductor.
10. Classify the following as a conductor, an insulator, or a semiconductor.
a) Aluminumb) Glassc) Copper
d) Rubbere) Germaniumf) Silicon
11. Classify each of the following by writing F if it is an example of charging an object by friction and C if it is an example of charging an object by contact.
a) Sliding across the seat of an automobile
b) Touching a charged rod to a metal sphere
c) Combing your hair with a plastic comb
d) Touching your hand to a slightly charged metal plate
12. By how much does the electric force between a pair of charged bodies change when their separation is
a) doubled? b) tripled? c) cut in half?
d) By how much does the electric force between a pair of charged bodies change when each charge is tripled?
13. The most common isotope of hydrogen contains a proton and an electron separated by about 5.0 x 10–11 m. The mass of a proton is approximately 1.67 x 10–27 kg. The mass of the electron is approximately 9.11 x 10–31 kg.
a) Use Newton's law of universal gravitation (F = Gm1m2/d2; G = 6.67 x 10–11) to calculate the gravitational force between the electron and proton in the hydrogen atom.
b) Use 1.6 x 10–19 C as the elementary unit of charge to determine the force of attraction between the two particles.
c) How many orders of magnitude greater is the electric force between the two particles than the gravitational force between the two particles? How important are gravitational force effects in this case?
14. Two charged spheres are on a frictionless horizontal surface. One has a charge of +3.0 μC, the other a +6.0 μC charge. Sketch the two spheres, showing all forces on them. Make the length of your force arrows proportional to the strength of the forces.
15. Two positive charges of 6.0 x 10–6 C are separated by 0.50 m. Draw a force diagram for each of the charges, considering only electrostatic forces. What is the magnitude of the force between the charges? Is this force repulsive or attractive?
16. A negative charge of 2.0 x 10–4 C and a positive charge of 8.0 x 10–4 C are separated by 0.30 m. What is the magnitude of the force between the charges? Is this force repulsive or attractive?
Assignment 7DO NOT WRITE ON THIS PAPER!!
Figure 1Figure 2
Assignment 7DO NOT WRITE ON THIS PAPER!!
18. Determine the magnitude and direction of the netelectrostatic force on charge q2 in Figure 2. As part of the solution, include a force diagram. (q1 = +45.0 µC; q2 = –12.0 µC; q3 = +18.0 µC)
19. Calculate the size of the force that would be experienced by a 3.0 C charge placed into a uniform electric field of strength 1.0 x 105 N/C.
20. A – 5.0 mC charge travels due south under the influence of a 10. N force when placed into a uniform electric field. What force would a
10. mC charge experience if placed in the same field and in which direction would it move?
21. What is the magnitude of a point charge that would create an electric field of 1.00 N/C at points 1.00 m away?
22. Consider a fixed point charge of +2.00 μC. What is the magnitude and direction of the electric field at a point P, a distance of 0.100 m away?
23. An electric field has an electric field strength 6000. N/C at a distance of 1.5 m. What is the strength of the field at a distance of 6.0 m?
24. An alpha (α) particle is positioned in an electric field such that the gravitational force acting on it is equal to the electrostatic force.
(qα = 3.2 x 10–19 C and mα = 6.64 x 10–27 kg)
a) What is the direction of the electric field at this point?
b) What is strength of the electric field?
c) If the field is located 0.25 m away, what is the magnitude of the charge?
25. Determine the potential at a point 0.50 m from a 20 µC point charge.
26. An electric field is parallel to the x-axis. What is the magnitude and direction of the electric field if the potential difference between x = 1.0 m and x = 2.5 m is found to be +900 V?
27. A charged droplet of mass 5.88 x 10–10 kg is hovering motionless between two parallel plates. The parallel plates create have a potential difference of 24000 V and are 2.00 mm apart. What is the charge on the particle?
28. Two parallel plates 2.1mm apart, are charged so that the potential difference between the plates is 36V.
a) What is the electric field strength between the plates?
b) A small particle charge of +180nC is placed midway between the plates. Find the force on the particle due to the electric field.
29. A potential difference of 1.00 x 104 V exists between two parallel plates which are separated by 10.0 cm. An electron (me = 9.11 x 10–31 kg) is released from the negative plate at the same instant a proton (mp = 1.67 x 10–27 kg) is released from the positive plate.
a) What is the electric field strength between the plates?
b) What is the acceleration of each particle?
Answers
3) 1213a) 4.1 x 10–47 N13b) – 9.2 x 10–8 N
13c) 2.2 x 103915) 1.3 N repulsive
16) 16000 N attractive17) 11.6 N right
18) 0.582 N, 21.8º NE19) 0.30 N
20) 20 N, south21) 1.11 x 10–10 C
22) 1.80 x 106 N/C23) 375 N/C
24a) up24b) 2.0 x 10–7 N/C24c) 1.4 x 10–18 C
25) 3.6 x 105 V26) 600 N/C27) 4.8 x 10–16 C
28a) 17,000 N/C28b) 0.0031 N
29a) 1.00 x 105 N/C
29b) p+ = 9.58 x 1012 m/s2, e- = 1.76 x 1016 m/s2