ap physics 1 study guides

๐Ÿงย  Multiple Choice Questions (MCQs)

8.3 Electric Force

#coulomb'slaw

#electricity

#force

#electrostaticconstant

โฑ๏ธย ย 2 min read

written by

Peter Apps

peter apps

April 16, 2020


Enduring Understanding 3.C

At the macroscopic level, forces can be categorized as either long-range (action-at-a-distance) forces or contact forces.

Essential Knowledge 3.C.2

Electric force results from the interaction of one object that has an electric charge with another object that has an electric charge.

Coulombโ€™s Law

As described in 8.2, charged objects attract or repel each other based on their charges. Coulombโ€™s Law lets us calculate the amount of force this attraction or repulsion exerts.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2FScreen%20Shot%202020-04-15%20at%209.44.58%20PM.png?alt=media&token=8d6ae9c8-8190-4922-92d8-51c109e72369

In the equation above:

  • F = Force in Newtons

  • k = Electrostatic Constant (on your reference tables)

  • q = charge on the objects in Coulombs

  • r = distance between the objects in meters

This equation leads to the following conclusions:

  1. More charge => More Force

  2. More distance => Less Force (Inverse Square Law, see graph below)

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2FScreen%20Shot%202020-04-15%20at%209.46.32%20PM.png?alt=media&token=53c549e7-5874-40e0-9811-9ce2111a5004

Just as a review, there are many similarities between this electrostatic force equation and Newtonโ€™s law of Universal Gravitation. Both equations are inverse square laws (meaning they both have an r^2 term in the denominator). The key differences between them are that k is significantly greater than G (about 10^20 times larger) and that Fe can be attractive or repulsive. The fact that Fe is so much greater than Fg means that it only takes a small amount of charge difference to have a noticeable electrostatic force, while to see a gravitational attraction takes very large amounts of mass.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2FScreen%20Shot%202020-04-15%20at%209.50.08%20PM.png?alt=media&token=85764336-03f9-499e-96e9-e5c91163b8e6

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2FScreen%20Shot%202020-04-15%20at%209.50.38%20PM.png?alt=media&token=95ffba08-ab64-4933-835d-951f81aacdb0

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2FScreen%20Shot%202020-04-15%20at%209.51.09%20PM.png?alt=media&token=7d5de561-31b9-415f-ae52-4b99e1a25ac1

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2FScreen%20Shot%202020-04-15%20at%209.52.08%20PM.png?alt=media&token=5965754e-7ad2-4e8c-97a5-d2224c4ac204

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2FScreen%20Shot%202020-04-15%20at%209.52.43%20PM.png?alt=media&token=0ccc6a20-d10b-45f8-a018-53d17f649be1

Watch AP Physics live streams here for more help.

Fiveable

Join Our Community

Fiveable Community students are already meeting new friends, starting study groups, and sharing tons of opportunities for other high schoolers. Soon the Fiveable Community will be on a totally new platform where you can share, save, and organize your learning links and lead study groups among other students!๐ŸŽ‰

Fiveable Logo

2550 north lake drive
suite 2
milwaukee, wi 53211

92% of Fiveable students earned a 3 or higher on their 2020 AP Exams.

*apยฎ and advanced placementยฎ are registered trademarks of the college board, which was not involved in the production of, and does not endorse, this product.

ยฉ fiveable 2020 | all rights reserved.