Physics Trivia : Physics Trivia Lightning is responsible for a number of deaths and injuries of people and livestock each year. A great percentage of lightning casualties is caused by standing tall trees during a rain. A person lucky enough to survive lightning strike is most likely to suffer the following: burns, paralysis and amnesia, eye damage chronic ear infection to hearing loss or muscle or ligament tears. Cardio pulmonary arrests is the primary cause of death following lightning strike. Motive Question : Motive Question What force is responsible for keeping objects intact? What force is so strong that it can even be a billion, billion, billion, billion times strong than gravity? What force exist between all charged particles? Slide 3: One of the strongest fundamental forces in nature is the electromagnetic force. Electrostatic force is the manifestation of this force which involves the interaction of electric charges that are stationary. Unlocking of Difficulties : Unlocking of Difficulties COULOMB’S LAW : COULOMB’S LAW Slide 6: It was studied and first published in 1783 by French physicist Charles Augustine de Coulomb and was essential to the development of the theory of electromagnetism. Slide 7: Diagram describing the basic mechanism of Coulomb's law; like charges repel each other and opposite charges attract each other. Slide 8: His conclusions can be summarized as Coulomb’s law of electrostatics:
“the force of attraction between two charged objects is directly proportional to the product of their charge magnitudes and inversely proportional to the square of the distance between them” If a proportionality constant is introduced, Coulomb’s law becomes: : If a proportionality constant is introduced, Coulomb’s law becomes: F = k q1q2 d2 K = 9.0 x 109 (Nm2/C2) Example : Example Example A
Suppose that two point charges, each with a charge of +1.00 Coulomb are separated by a distance of 1.00 meter. Determine the magnitude of the electrical force of repulsion between them. Slide 12: Given:
Q1 = 1.00 CQ2 = 1.00 C
d = 1.00 m Find:
Felect = ? F = (9.0 x 109 N•m2/C2) (1.00 C) • (1.00 C) (1.00 m)2 Answer : Answer Felect = 9.0 x 109 N Example : Example Example B
Two balloons with charges of +3.37 µC and -8.21 µC attract each other with a force of 0.0626 Newton. Determine the separation distance between the two balloons. Given:Q1 = +3.37 µC = +3.37 x 10-6CQ2 = -8.21 µC = -8.21 x 10-6 CF = -0.0626 N (use a (-) force value since it is repulsive) : Given:Q1 = +3.37 µC = +3.37 x 10-6CQ2 = -8.21 µC = -8.21 x 10-6 CF = -0.0626 N (use a (-) force value since it is repulsive) Find:
d = ? Answer : Answer d = 1.99 m Exercises : Exercises 1. Determine the electrical force of attraction between two balloons with separate charges of +3.5 x 10-8 C and -2.9 x 10-8 C when separated by a distance of 0.65 m. ANSWER : ANSWER -1.85 x 10-5 N Slide 19: 2.Determine the electrical force of attraction between two balloons that are charged with the opposite type of charge but the same quantity of charge. The charge on the balloons is 6.0 x 10-7 C and they are separated by a distance of 0.50 m. ANSWER : ANSWER 1.30 x 10-2N Slide 21: 3. What is the charge of the body that will repel another body of charge 6.4 x 10-6 C with a force of 2.7 x10-1 N when they are 0.84 m. apart? Answer : Answer 3.31 x 10-6 C Evaluation… identify the ff: : Evaluation… identify the ff: 1. He is a French physicist who discovered the inverse square relationship between distance and the product of the two charged body.
2. The kind of force that exists between two negatively charged body. Slide 24: 3. The relationship between the force and the distance between two charged object.
4. Unit of charged body.
5. Formula of coulomb’s law. Agreement : Agreement Read, understand and analyze the problem below. Then solve and show your complete solution.
A Hydrogen atom is composed of an electron and proton. The Bohr radius, the radius of a hydrogen atom is 5.30 x 10-11m. What is the force of attraction between the proton and the electron in the atom?