6. (1 points) Pennies today are made of copper-covered zinc, but older pennies c

Question

6. (1 points) Pennies today are made of copper-covered zinc, but older pennies contain 3.1 g of pure solid copper. What are the total positive charge and total negative charge in an older solid copper penny that is electrically neutral? (Hint: you will need to look up Avogadro's Number and the molar mass of copper.) 7. (3 points) A-120G charge is located at Cartesian coordinates (x, (1.0 cm, 0 cm). What are the electric fields at the three positions X, 3 (5.0 cm, 0 cm), (-5.0 cm, 0 cm), and (0 cm, 5.0 cm)? Write each electric field vector in component form (using the unit vectors i and j) 8. (2 points) The nucleus of a 12 Xe atom (an isotope of the element xenon with mass 125 u) has a and a proton as point charges for the purposes of this problem.) a. What is the electric force on a proton 2.0 fm from the surface of the nucleus? b. What is the proton's acceleration? 9. (2 points) A 0.10 g honeybee acquires a charge of +23 pawhile fying. field the surface is typically (100 NMC, downward) What is the ratio of the electric force on the bee to the bee's weight? b. Determine the strength and direction of the electric feld that vould allow the bee to hang suspended motionless in the air without moving its wings 10. (3 points) Two 5.0 g point charges on 1.0-m-long threads repel each other after being charged to +100 0C, as in the figure below. 616 1.0 m I 1.0m 5.0 g 5.0 g 100 nC 100 mC The dotted vertical line bisects the angle 20. What is the angle 0? (Hint: You can assume that e is less than 109, and then use the small angle approximation that says that tan e sin efor small e.)

Explanation / Answer

Q6.

molar mass of copper=63.546 grams

so 3.1 grams of copper will have (3.1/64.546)=0.04878 moles of copper

1 mole=6.023*10^23 atoms

hence total number of copper atoms in 3.1 grams=2.93823*10^22

an atom of copper has 29 protons and 29 electrons

so total positive charge of 3.1 grams of copper=number of atoms

*number of proton per atom*charge per proton

=2.93823*10^22*29*1.6*10^(-19)=136334.0446 C

as the mass is charge neutral, equal magnitude of negative charge will be there

hence negative charge=-136334.0446 C

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