http://www.ck12.org Chapter 16. Static Electricity
Practice problems on Coulomb’s Law: http://physics.info/coulomb/problems.shtml
Review
Questions
- Suppose that two point charges, each with a charge of +1.00 C, are separated by a distance of 1.0 m:
(a) Will the charges attract or repel?
(b) What is the magnitude of the force between them?
(c) If the distance between them is doubled, what does the force become? - What is the electrical force between two balloons, each having 5.00 C of charge, that are 0.300 m apart?
- Two spheres are charged with the same charge of -0.0025 C and are separated by a distance of 8.00 m. What
is the electrical force between them? - A red foam ball and a blue foam ball are 4.00 m apart. The blue ball has a charge of 0.000337 C and is
attracting the red ball with a force of 626 N. What is the charge on the red ball?
- Coulomb’s Law:States the force of attraction or repulsion acting along a straight line between two electric
charges is directly proportional to the product of the charges and inversely to the square of the distance between
them.
Matter is made up of atoms, which consist of small, charged particles. The tightly held, heavier, positively charged
particles are called protons, while the loosely held, lighter, negatively charged particles are called electrons. When
there are excess electrons in an object, it is considered to be negatively charged; when there is a deficit of electrons,
the object is considered positively charged. Charged objects exert a force on each other, which can be calculated
based on the objects’ charges and distance from each other using Coulomb’s law. Some materials transmit electrons
easily and are called conductors, while other materials, called insulators, restrict the transmission of electrons.