Static Electricity and Number of Electrons

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SUMMARY

The discussion centers on calculating the ratio of electrons added to a gold sphere after it is rubbed with rabbit's fur, resulting in a net charge of 0.540 μC. The mass of the gold sphere is 190.0 g. The user initially attempts to calculate the number of electrons originally present using the formula involving the mass of gold and the mass of an electron (9.11e^-31 kg). The correct approach involves determining the number of gold atoms and the electrons per atom, which leads to a more accurate calculation of the ratio.

PREREQUISITES
  • Understanding of electric charge and its units (microcoulombs)
  • Knowledge of atomic structure, specifically gold atoms and their electron configuration
  • Familiarity with basic physics equations related to charge and mass
  • Proficiency in unit conversions, particularly between grams and kilograms
NEXT STEPS
  • Calculate the number of atoms in 190.0 g of gold using Avogadro's number.
  • Determine the total number of electrons in a single gold atom.
  • Learn about the principles of static electricity and charge transfer.
  • Explore the concept of charge neutrality and its implications in physics.
USEFUL FOR

Students studying physics, particularly those focusing on electrostatics, as well as educators seeking to enhance their understanding of charge interactions and atomic structure.

Nicolaus
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Homework Statement


When you rub a gold sphere with rabbit's fur, the gold takes on a negative charge (and the rabbit fur positive). Suppose the gold sphere has a mass of 190.0 g and it obtains a net charge of 0.540 μC. Calculate the ratio of the number of electrons added to the gold sphere to the number originally there. (Assume the gold sphere is completely neutral before the fur is applied.)

Homework Equations





The Attempt at a Solution


.190kg(9.11e^-31kg) = # electrons before
5.4e^-5C / (1.602e^-19) = electrons added

Then divide electrons added by electrons when neutral.
What am I doing wrong?
 
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Nicolaus said:

Homework Statement


When you rub a gold sphere with rabbit's fur, the gold takes on a negative charge (and the rabbit fur positive). Suppose the gold sphere has a mass of 190.0 g and it obtains a net charge of 0.540 μC. Calculate the ratio of the number of electrons added to the gold sphere to the number originally there. (Assume the gold sphere is completely neutral before the fur is applied.)

Homework Equations





The Attempt at a Solution


.190kg(9.11e^-31kg) = # electrons before
5.4e^-5C / (1.602e^-19) = electrons added

Then divide electrons added by electrons when neutral.
What am I doing wrong?

Think again about the number of electrons originally present in the sphere of gold. How many atoms of gold are present? How many electrons per atom?
 
Ah, got this.
Thanks
 

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