EntrancePresentation on the topic "Coulomb's law". Section of the presentation on the topic of Coulomb's law Presentation of Coulomb's law electric field
Coulomb's law
Prepared by:
Klimanova Olga Gennadievna
Physics teacher
Municipal educational institution Zakharovskaya secondary school No. 2
- Using a physical model - a “point charge”, establish the quantitative dependence of the interaction of two stationary charged bodies located in a vacuum.
Lesson Objectives
Educational:
- to form students’ knowledge about a point charge, about the force of interaction between charges;
- show the dependence of the force of interaction between electric charges on their value and on the distance between them;
- explain the physical meaning of Coulomb's law;
- indicate the limits of applicability of the law;
- teach how to solve problems using Coulomb's law.
Educational:
- develop students’ skills to observe, analyze, generalize, compare cognitive objects, and draw conclusions;
- develop the ability to exercise self-control, self-assessment and self-correction of educational activities.
Educational:
- instill responsibility in students;
- independence.
Charles Augustin Pendant (1736-1806)
French engineer and physicist, one of the founders of electrostatics.
Invented (1784) torsion balances and discovered (1785) the law of two stationary point charged bodies.
Coulomb's experimental studies were fundamental to the formation of the doctrine of electricity and magnetism.
Point charge
Point charges are called charged bodies whose dimensions are much less than the distance between them.
Coulomb's experiment
When message the balls a And b charges of the same name, they begin to repel each other. To keep the balls at a fixed distance, the elastic wire is twisted at a certain angle. The force of interaction between the balls is determined by the angle of twist of the wire.
Torsion balances made it possible to study the dependence of the interaction force of charged balls on the values of the charges and on the distance between them.
Formulation of Coulomb's law
The force of interaction between two point charges in a vacuum is directly proportional to the product of the charge moduli and inversely proportional to the square of the distances between them.
For vacuum: ε = 1
- What does Coulomb's law define?
- How is Coulomb's law written for the interaction of charges in a vacuum?
- What quantity characterizes the influence of the environment on the force of interaction between charges?
- Write Coulomb's law for the interaction of charges taking into account the environment in the SI system?
- What is the coefficient of proportionality in Coulomb's law?
- How will the force of the Coulomb interaction of two point charges change when each charge increases by a factor of 3, if the distance between them is reduced by a factor of 2?
- With what force do two charges interact? 10 nC located at a distance 3 cm from each other?
- How far apart are the charges from each other? 1µC And 10 µC, interact with force 9mN.
Reflection
Continue the phrases:
- I was wondering...
- Today we figured it out...
- I realized today that...
- It was difficult for me...
- Tomorrow I want in class...
Homework
§ 87 – 88, ex. 16
Thank you for your attention!
PHYSICS LESSON IN 10TH GRADE
- Electrification. Coulomb's law
- Teacher Kononov Gennady Grigorievich
- Secondary school No. 580 Primorsky district St. Petersburg
- Atomic structure
- Electrification of bodies
- Law of conservation of charge
- Coulomb's law
- Independent work (6min)
- 1. Light, radio waves, television
- 2. Holds atoms and molecules
- 3. Elasticity and friction forces
- 4. Chemical reactions
- 5. Electric motors
- 1. When electrified both bodies are charged participating in it
- 2. Electrification– this is the process of bodies receiving charges during interaction (friction, impact, touch, irradiation)
- 3. Degree of electrification characterized by the sign and magnitude of the electric charge
ATOMIC STRUCTURE
- At the center of the atom there is a positively charged nucleus around which electrons revolve
- The charge on the protons in the nucleus is equal to the charge on the electrons orbiting the nucleus, so the atoms are neutral.
- An atom can lose electrons (positive ion), or gain extra ones (negative ion)
- There are two types of electric charges, conventionally called positive and negative.
- Charges can be transferred from one body to another. ( Unlike body mass, electric charge is not an integral characteristic of a given body. The same body under different conditions can have a different charge).
- Like charges repel, unlike charges attract. ( This also reveals the fundamental difference between electromagnetic forces and gravitational ones. Gravitational forces are always attractive forces).
- In an isolated system, the algebraic sum of the charges of all bodies remains constant: q 1 + q 2 + q 3 + ... +q n = const. Applications:
- Nuclear reactions
- Dissociation reaction
- Two identical balls with charges 3e and – 7e were brought into contact and moved apart. What is the charge on the balls?
- Given: Solution Q1 = 3e Q1 + Q2 = q1 + q2 q1 = q2 Q2 = - 7e q1 = (Q1 + Q2):2 q1 , q2 - ? q1 = q2 = (3e – 7e):2 = - 2e
F – interaction force (N)
k = 9·10 - coefficient
q1, q2 – body charges (C)
ε – dielectric
medium permeability
r – distances between
charges (m)
1 COULLOMB'S LAW
- The interaction forces between stationary charges are directly proportional to the product of the charge modules and inversely proportional to the square of the distance between them
- Interaction forces obey Newton's third law: F1 = - F2 They are repulsive forces with the same signs of charges and attractive forces with different signs
- Given: C Solution q1 = 10nC 10·10 C q2 = 15nC 15·10 C r = 5cm 0.05m F - ? Answer: 0.54 mN
TASK 3 INDEPENDENT WORK
- 1. Write last name and option
- 2. There are 6 questions and 4 answers each 3. There is only one correct answer
- 4. For giving hints and for using someone else’s answer, the score is reduced.
- 5. Each question is given 1 minute (60s)
- 6. Slides change automatically.
- 1. The time allotted for completing the work has expired.
- 2. Check for last name and variant number
- 3. Submitted your work
- 4. Thank you for your work
- 5. We will analyze the correct answers into next lesson
- §85 – 88
- Learn formulas and definitions
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Coulomb's Law - presentation by teacher Co...
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Lesson topic: Coulomb's law. Unit of electric charge .
Purpose of the lesson: - study Coulomb’s law, learn to apply it to solve problems in electrostatics.
Charles Augustin Pendant
(14.06.1736 – 23.08.1806)
French physicist, military engineer, known for his experiments on electricity and magnetism and his study of friction forces.
In 1785 he established the fundamental law of electrostatics.
Coulomb's law -
Coulomb force is central .
Electric charge is physical quantity .
Denoted by the letter q
The unit of electric charge is taken pendant (Cl)
1 C is a charge passed through the cross-section of a conductor in 1 s at a current of 1 A; 1 C = 1 A 1s .
k – coefficient
proportionality
Physical meaning of k: F = k , If r =1 m, q 1 = q 2 =1Kl
Limits of applicability of Coulomb's law:
- The law is valid for point charges. If the sizes and distances are commensurate, then Coulomb’s law does not apply.
2. Charged bodies must be motionless because When charged bodies move, the action of the magnetic field that arises as a result of the movement is manifested.
Coulomb's law - The force of interaction between two stationary point charges in a vacuum is directly proportional to the product of the charge moduli and inversely proportional to the square of the distance between them.
1. How do you understand the expression “Force is directly proportional to the product of charge modules”?
2. How do you understand the expression “Force is inversely proportional to the square of the distance between charges”?
- In which picture are the charges pointlike?
4. In what case is Coulomb’s law true? Why?
5. How will the force of the Coulomb interaction change if...
A) the value of one of the charges will increase by 2 times;
B) the value of one of the charges will increase by 3 times, and the second will decrease by 9 times;
C) the distance between charges will increase 6 times;
5 correct answers – “5”
4 correct answers - “4”
Words for evaluating work:
active passive
responsible irresponsible
enthusiastically indifferent
consciously unconsciously
effective to no avail
thoughtfully superficial
Troubleshooting work:
- learn the definition, formula, ...;
- consult with the teacher on the issue...,
Homework:
1. §85-86, questions after the paragraph.
2. On the website http://interneturok.ru watch the lesson “Coulomb’s Law” - optional
3. On the website http://www.fipi.ru/content/otkrytyy-bank-zadaniy-ege in the “Physics” section, Electrostatics. Select 3 problems using Coulomb's law and write down their solutions in your notebooks.
Thanks for the lesson.
It was a pleasure working with you.