Summary Electrostatic forces and electric fields notes IEB & DBE notes
17 views 0 purchase
Course
Physical Sciences
Institution
12th Grade
This document contains detailed notes on Coulomb’s law, Newton’s law of universal gravitation and electric fields. Detailed explanations and examples are given on the following:
Laws and definitions
Formulae and units
Theory questions
Staggered and Multiple choice question examples
Fi...
, Electrostatics
Coulombs law
Coulomb's law: Two point charges in free space or air exert forces on each other. The force is
directly proportional to the product of the charges and inversely proportional to the square of
the distance between the charges
Formula: F: force of attraction between q1 & q2 (unit: N)
9 -2
F = k.q1.q2 k: coulomb’s constant, 9x10 N.m2.C
q: magnitude of charge (unit: C) NB! Don’t add positive/negative
r 2
r: distance between the charges (unit: m)
Other formulae:
Substitute charge magnitude only. Include signs! Used to determine
Direction determined by nature of charge (repel, attract). Qnew = (Q1+Q2)/2 new charges after contact
-19 How many electrons
Both objects experience the same force (Newton’s 3rd Law). Ne- = Q/qe qe: 1,6x10 C present on each sphere
Example Unit change Micro- (µC): 9x10
-6
-9
Staggered question
-2
Centi- (Cc): 9x10 Nano- (nC): 9x10
-3 -12
Milli- (Mc): 9x10 Pico- (pC): 9x10
Sphere X carries a charge of -3nC & sphere Y
carries a charge of +4nC. After contact, they Multiple choice question
separate to 48mm. Calculate the repulsive Two charges experience a force F when held
force experienced by X after contact with Y. a distance r apart. How would the force be
35°
affected if one charge is doubled, the other
Y
-
48mm - X charge is tripled and the distance is halved.
F = k.q1.q2 F= (1)(1)(1) = 1N
r
To determine q1 & 2
-3 + (+4) /2 = +0,5nC q2 after contact
2 (1)
F = k.q1.q2 Swap all values with 1 to be able to compare!
r 2
F= (1)(2)(3)
9 2
= (9x10 )(0,5x10-9)(0,5x10-9 ) (0,5)
-3 2 Convert to m!
(48x10 ) = 24N
-7
= 9,77x10 N repulsion, X moved to the right Answer - 1:24
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller erinswanepoel. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.75. You're not tied to anything after your purchase.
