1. Physics 16/21 electromagnetism
Coulomb’s and Electric Force
MARLON FLORES SACEDON

2. How PHYSICS developed? 250 BCE Archimedes' principle: Archimedes
1589 Galileo's Leaning Tower of Pisa experiment: Galileo Galilei
1613 Inertia: Galileo Galilei
1687 Laws of Motion and Law of Gravitation and calculus: Isaac Newton
1820 Evidence for electromagnetic interactions: André-Marie Ampère, Jean-Baptiste Biot, Félix Savart
1827 Electrical resistance, etc.: Ohm
1831 Electromagnetic induction: Michael Faraday
1847 Conservation of energy: James Prescott Joule, Hermann von Helmholtz
1887 Electromagnetic waves: Heinrich Rudolf Hertz
1879 Hall Effect: American physicist Edwin Hall (The start of sensor)
1895 X-rays: Wilhelm Röntgen
1905 Special relativity: Albert Einstein
Photoelectric effect: Albert Einstein
1913 Bohr Model of the atom: Niels Bohr
1926 Schrödinger Equation: Erwin Schrödinger

3. SENSORS How PHYSICS developed?
SENSORS is an electronic component, module, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. A sensor is always used with other electronics, whether as simple as a light or as complex as a computer.

4. Sensors Hall Magnetic Field Sensor Temperature Sensor
Full Color RGB LED Module
Optical Tracking Sensor
Infrared Obstacle Avoidance Sensors
Infrared Transmitter Module
Laser Transmitter Module
Sound Sensor Module
Bluetooth Sensor Module
Infrared-Receiver Module
Photo-Interrupter Sensor Module
Mercury Tilt Switch Module
Flame Sensor
Relay Module
Touch Sensor Module
Digit Light Sensor
Temperature Humidity Sensor
Reed Switch Module
Smoke Sensor
Garden Soil Moisture Sensor

5. Development in Physics
PIR is an electronic sensor that measures infrared (IR), the ambient amount radiated from the room or walls or outdoors. When a warm body like human or animals passes by.
Photo sensor: Passive Infrared (PIR)

6. Distance Sensor: (Ultrasonic distance sensor)
Ultrasonic sensor is a device that can measure the distance to an object by using sound waves. It measures distance by sending out a sound wave at a specific frequency and listening for that sound wave to bounce back.

7. Development in Physics
Microcomputer: (Microprocessor)

8. Arduino software IDE

9. Development in Physics
SAMPLE OF ARDUINO PROJECT

10. What is electromagnetism?
A branch of physics which involves the study of the interactions between charges.

11. Objective: To study the principles of Coulomb’s Law
To calculate electric force using the principle of Coulomb’s law.

12. Law of electric charges
Two positive charges or two negative charges repel each other.
2. A positive charge and a negative charge attract each other.
3. Uncharge material is always attracted by a charge material.

13. Law of electric charges

14. conductors, insuLators, and induced charges
Conductors conduct electrical current very easily because of their free electrons. Some common conductors are copper, aluminum, gold, and silver.
Insulators oppose electrical current and make poor conductors. Some common insulators are glass, air, plastic, rubber, and wood.
There are a variety of methods to charge an object. One method is known as induction. In the induction process, a charged object is brought near but not touched to a neutral conducting object. The presence of a charged object near a neutral conductor will force (or induce) electrons within the conductor to move. This process is called Induced Charges or Electric Charging.

15. Charging by conduction
Charging by induction

16. electric charge and the structure of Matter
Mass of electron = me = 9.11x10-31 kg
Mass of proton = mp = 1.673x10-27 kg
Mass of neutron = mn = 1.675x10-27 kg
Charge of One electron: e=1.602𝑥 10 −19 𝐶/electron
Principle of conservation of charge:
The algebraic sum of all the electric charges in any closed system is constant.

17. Periodic Table Atomic number
Charge of One electron: e=1.602𝑥 10 −19 𝐶/electron
Where:
𝑚 𝑡𝑜𝑡 = total mass (g)
𝑛 = number of moles (mol)
𝑀 = molar mass (g/mol)
𝑁 𝐴 = x1023 atoms/mol
Abogadro’s number
𝑁 = number of atom in a substance
𝑚 𝑡𝑜𝑡 =nM
𝑁=𝑛 𝑁 𝐴
Periodic Table
Problem: Excess electrons are placed on a small lead sphere with mass 8.00𝑔 so that its net charge is −3.39𝑥 10 −9 𝐶. (a) Find the number of excess electrons on the sphere. (b) How many excess electrons are there per lead atom?
= −3.39𝑥 10 −9 𝐶 1.602𝑥 10 −19 𝐶/electron
a) Number of excess electron on lead sphere = 𝑞 𝑒
= 2.00𝑥 electrons
b) Number of excess electron per lead atom, 𝑁?
= 8.00𝑔 𝑔/𝑚𝑜𝑙
𝑛= 𝑚 𝑡𝑜𝑡 𝑀
= 𝑚𝑜𝑙
𝑁=𝑛 𝑁 𝐴
= 𝑚𝑜𝑙(6.022 𝑥1023 𝑎𝑡𝑜𝑚𝑠/𝑚𝑜𝑙)
=2.328𝑥 𝑎𝑡𝑜𝑚𝑠
Number of excess electron per lead atom, N = 2.00𝑥 electrons 2.328𝑥 𝑎𝑡𝑜𝑚𝑠
=8.59𝑥 10 −13 electron/atom

18. Interaction of masses [Mechanics]
Interaction of charges [Electromagnetism] m 𝐹𝑔
𝑈(Gravitational Potential Energy)
𝐾(Kinetic energy)
𝑈(Electric Potential Energy) +q Fe
𝑊(Workdone)
𝐾(Kinetic energy)
(Gravitational force)
𝑉(Electric potential)
𝜏 (Torque)
𝑝 (momentum)
𝑔 =9.81𝑚/𝑠2
𝐸 (Electric field)
(Electric force or coulomb force)
𝑒𝑡𝑐..)
(Gravitational acceleration)
- Q m Fg

19. Interaction of masses [Mechanics] 𝐹𝑔 Fg
𝑔 =9.81𝑚/𝑠2
Interaction of masses [Mechanics]
𝑈(Gravitational Potential Energy)
(Gravitational force)
(Gravitational acceleration)
𝐾(Kinetic energy)
Interaction of charges [Electromagnetism]
𝑈(Electric Potential Energy) +q Fe
𝑊(Workdone)
𝐾(Kinetic energy)
𝑉(Electric potential)
- Q
𝜏 (Torque)
𝑝 (momentum)
𝐸 (Electric field)
𝑒𝑡𝑐..)
- Q

20. Interaction of masses [Mechanics] 𝐹𝑔 Fg
𝑔 =9.81𝑚/𝑠2
Interaction of masses [Mechanics]
𝑈(Gravitational Potential Energy)
(Gravitational force)
(Gravitational acceleration)
𝐾(Kinetic energy)
Interaction of charges [Electromagnetism] +q Fe
𝑈(Electric Potential Energy)
𝑊(Workdone)
𝐾(Kinetic energy)
𝑉(Electric potential)
𝜏 (Torque)
𝑝 (momentum)
𝐸 (Electric field)
𝑒𝑡𝑐..)
+ Q

21. Coulomb’s law
Coulomb's law, or Coulomb's inverse-square law, is a law of physics describing the electrostatic interaction between electrically charged particles. The law was first published in 1785 by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism.
Coulomb’s torsion balance

22. Coulomb’s law 𝐹 =𝑘 𝑞 1 𝑞 2 𝑟 2 𝑟 Electric force vector 𝑞 2 𝐹 12 - 𝐹 21+
𝑞 1
𝐹= 1 4𝜋 𝜖 𝑜 ∙ 𝑞 1 𝑞 2 𝑟 2
𝐹∝ 𝑞 1 𝑞 2 𝑟 2
𝐹=𝑘 𝑞 1 𝑞 2 𝑟 Magnitude of electric force
𝑞 2
𝐹 =𝑘 𝑞 1 𝑞 2 𝑟 2 𝑟 Electric force vector
𝐹 12
𝐹 21
𝐹 12 +
𝑞 1 =+25𝑛𝐶 -
𝑞 2 =−75𝑛𝐶
𝑟=3.0𝑐𝑚 + 𝑟
𝑞 1
Where: 𝑘 is electric constant +
𝐹 21
(Coulomb’s law: force between two point charges)
𝑞 1 𝑎𝑛𝑑 𝑞 2 are interacting charges, in 𝐶𝑜𝑢𝑙 𝑜𝑟 𝐶
𝐹 12 =9𝑥 𝑁∙ 𝑚 2 𝐶 𝑛𝐶 75𝑛𝐶 3𝑐𝑚 2
1 coul = x 109 statC
𝜖 𝑜 =8.854𝑥 10 −12 𝐶 2 𝑁∙ 𝑚 2
𝐹 12 =9𝑥 𝑁∙ 𝑚 2 𝐶 𝑥 10 −9 𝐶 75𝑥 10 −9 𝐶 3𝑥 10 −2 𝑚 2
Permittivity of free space
Problem: Two point charges, 𝑞 1 =+25𝑛𝐶 and 𝑞 2 =−75𝑛𝐶, are separated by a distance 𝑟=3.0𝑐𝑚. Find the magnitude of the electric force (a) that 𝑞 1 exerts on 𝑞 2 and (b) that 𝑞 2 exerts on 𝑞 1 .
1 4𝜋 𝜖 𝑜 =𝑘=8.988𝑥 𝑁∙ 𝑚 2 𝐶 2
𝐹 12 = 𝑁 attractive force
𝐹 21 =9𝑥 𝑁∙ 𝑚 2 𝐶 𝑥 10 −9 𝐶 +25𝑥 10 −9 𝐶 3𝑥 10 −2 𝑚 2
𝑘=9𝑥 𝑁∙ 𝑚 2 𝐶 2
𝑘=1 𝑑𝑦𝑛𝑒∙𝑐 𝑚 2 𝑠𝑡𝑎𝑡𝐶 2
𝐹 21 = 𝑁 attractive force

23. Coulomb’s law Superposition of electric charge 𝑦 𝑥
𝐹= 1 4𝜋 𝜖 𝑜 ∙ 𝑞 1 𝑞 2 𝑟 2 -
−𝑞 3
𝑟 13
𝐹 21 = 1 4𝜋 𝜖 𝑜 ∙ 𝑞 1 𝑞 𝑟 +
𝑞 2
𝐹 31 = 1 4𝜋 𝜖 𝑜 ∙ 𝑞 1 𝑞 𝑟 𝐹
𝐹 31
𝑟 12 +
𝑞 1
𝐹 21
𝐹 = 𝐹 𝐹 31
Note: vector sum or geometric sum not arithmetic sum

24. Coulomb’s law Example. 𝐹 = 𝐹 21 + 𝐹 31 = 𝐹 𝑥 𝑖 + 𝐹 𝑦 𝑗
Calculate the net electric force on charge 1 due to charge 2 & charge 3. 𝑦 𝑥
𝐹= 1 4𝜋 𝜖 𝑜 ∙ 𝑞 1 𝑞 2 𝑟 2
1 4𝜋 𝜖 𝑜 =𝑘=9𝑥 𝑁∙ 𝑚 2 𝐶 2 +
𝑞 3 =7𝑛𝐶
3cm
𝐹 21 =9𝑥 𝑁∙ 𝑚 2 𝐶 2 ∙ (3𝑛𝐶)(9𝑛𝐶) (6𝑐𝑚) 2
𝑟 13 = =5𝑐𝑚
𝑟 13
4cm
𝜃= 𝑇𝑎𝑛 − = 53.1 𝑜
=9𝑥 𝑁∙ 𝑚 2 𝐶 2 ∙ 3𝑥 10 −9 𝐶 9𝑥 10 −9 𝐶 6𝑥 10 −2 𝑚 2
=6.75𝑥 10 −5 𝑁 +
𝑞 1 =3𝑛𝐶 𝜃
𝑟 12 -
𝑞 2 =−9𝑛𝐶
𝐹 31 =9𝑥 𝑁∙ 𝑚 2 𝐶 2 ∙ (3𝑥 10 −9 𝐶)(7𝑥 10 −9 𝐶) (5𝑥 10 −2 𝑚) 2 𝜃 𝛽
=7.56𝑥 10 −5 𝑁
6cm
𝐹 31
𝐹 31
𝐹 = ?
Using component method:
=2.21𝑥 10 −5 𝑁
Σ 𝐹 𝑥 =6.75𝑥 10 −5 𝐶−7.56𝑥 10 −5 𝐶(cos 𝑜 )
=−6.06𝑥 10 −5 𝑁
Σ 𝐹 𝑦 =0−7.56𝑥 10 −5 𝐶(sin 𝑜 )
vector sum
𝐹= (2.21𝑥 10 −5 ) 2 + (6.06𝑥 10 −5 ) 2
=6.45𝑥 10 −5 𝑁
𝐹 = 𝐹 𝐹 31 = 𝐹 𝑥 𝑖 + 𝐹 𝑦 𝑗
Magnitude
𝛽= 𝑇𝑎𝑛 −1 Σ 𝐹 𝑦 Σ 𝐹 𝑥
= 𝑇𝑎𝑛 − 𝑥 10 − 𝑥 10 −5
𝐹 =(2.21𝑥 10 −5 𝑁) 𝑖 +(−6.06𝑥 10 −5 𝑁) 𝑗
𝐹 = 2.21𝑥 10 −5 𝑁 𝑖 − 6.06𝑥 10 −5 𝑁 𝑗 ANSWER
= 70 𝑜 from +x-axis in QIV
Direction

25. Coulomb’s law Assignment 1 Assignment 2
Two point charges are located on the +x-axis of a coordinate system: 𝑞 1 =1.0𝑛𝐶 is at 𝑥=+2.0𝑐𝑚, and 𝑞 2 =−3.0𝑛𝐶 is at 𝑥=+4.0𝑐𝑚. What is the total electric force exerted by 𝑞 1 and 𝑞 2 on a charge 𝑞 3 =5.0 𝑛𝐶 at 𝑥=0?
Assignment 2
Calculate the net electric force on charge 1 due to charge 2 & charge 3. Calculate also the magnitude and direction of the net force. 𝑦 𝑥 -
𝑞 4 =4𝜇𝐶 -
𝑞 3 =−6𝜇𝐶
5cm
4cm
𝑟 13
6cm
6cm +
𝑞 1 =3𝜇𝐶 𝜃
𝑟 12 -
𝑞 2 =9𝜇𝐶 𝜃
12cm

26. Problems/ assignment

27. Problems/ assignment

28. Problems/ assignment

29. Problems/ assignment

30. eNd