Worksheet: Charging by Induction

In this worksheet, we will practice determining the net charge resulting from unequal amounts of positive and negative charges acquired by induction.

Q1:

Suppose a speck of dust in an electrostatic precipitator has 1 . 0 0 × 1 0 protons in it and has a net charge of 5 . 0 0 nC. How many electrons does the speck of dust contain? The magnitude of the charge of protons and of electrons is 1 . 6 0 × 1 0 C.

  • A 1 . 0 3 × 1 0 e
  • B 3 . 1 2 × 1 0 e
  • C 3 . 1 2 × 1 0 e
  • D 1 . 0 3 × 1 0 e
  • E 1 . 3 2 × 1 0 e

Q2:

Determine how many coulombs of positive charge are contained in a lump of pure plutonium with a mass of 4.00 kg. Use a value of 244 g/mol for the atomic mass of plutonium and recall that the plutonium has an atomic number of 94.

  • A 1 . 7 6 × 1 0 8 C
  • B 1 . 6 1 × 1 0 8 C
  • C 1 . 9 0 × 1 0 8 C
  • D 1 . 4 9 × 1 0 8 C
  • E 2 . 0 3 × 1 0 8 C

Q3:

A copper atom has 29 protons and a neutral ball of copper has one electron per proton. Copper has an atomic mass of 63.5 unified atomic mass units. A unified atomic mass units is equivalent to 1 . 6 6 × 1 0 g.

How many electrons would be contained in a neutral copper ball with a mass of 50.0 g?

  • A 1 . 6 3 × 1 0
  • B 4 . 7 4 × 1 0
  • C 1 . 1 1 × 1 0
  • D 1 . 3 8 × 1 0
  • E 3 . 0 6 × 1 0

A copper ball with a mass of 50.0 g has a net charge of +2.00 µC. What percent of the electrons in the copper ball have been removed?

  • A 9 . 0 9 × 1 0 %
  • B 9 . 6 8 × 1 0 %
  • C 8 . 2 0 × 1 0 %
  • D 7 . 1 9 × 1 0 %
  • E 1 . 3 7 × 1 0 %

Q4:

A copper penny of mass 2.500 g is given a net charge of 2 . 0 0 0 × 1 0 9 C.

The charge of an electron is 1 . 6 0 2 1 × 1 0 1 9 C.

How many excess electrons are on the penny?

  • A 1 . 2 7 1 × 1 0 1 0 e
  • B 1 . 2 2 6 × 1 0 1 0 e
  • C 1 . 2 9 5 × 1 0 1 0 e
  • D 1 . 2 4 8 × 1 0 1 0 e
  • E 1 . 3 1 6 × 1 0 1 0 e

By what percent do the excess electrons change the mass of the penny?

  • A 4 . 5 4 8 × 1 0 % 1 6
  • B 5 . 1 1 4 × 1 0 % 1 6
  • C 4 . 9 1 1 × 1 0 % 1 6
  • D 4 . 7 2 8 × 1 0 % 1 6
  • E 5 . 2 1 0 × 1 0 % 1 6

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