Chapter 1: Introduction and DC Circuit

1. Chapter 1:Introduction and DC Circuit AZRALMUKMIN BIN AZMI

2. Chapter 1.1:Current, Voltage, Resistance, Conductor, Insulator, Active & Passive Element AZRALMUKMIN BIN AZMI

3. Electric Charge (Q) • Atom: Electron (negative charge) Proton (positive charge) • The orbiting -ve charge (electron) = magnitude of +ve charge (proton) • Electric charge create electric field of forced • Electric charge is an electrical property of atomic particles of which matter consists measure in Coulombs (C) • Opposite charge = attract same charge = keep away

4. Electric Charge (Cont…) • 1 coulomb (C) = total charge associated with 6.242 x 1018 electrons.

5. Current (I) • Define = movement of charge in specific direction I = current (A) Q = charge (C) t = time (s) Unit = Ampere (A)

6. Current (I) (Cont…) • Type of current: - Direct Current (DC) current remain constant with time - Alternating Current (AC) current that varies sinusoidal with time

7. Current (I) (Cont…) • Current source Device that can generate a prescribe current independent of the circuit which is connected.

8. Voltage (V) • Define = how much energy is involve in moving a charge between 2 point in electrical system V = voltage (V) W = energy (J) Q = electric charge (C) Unit = Volt (V)

9. Voltage (V) (Cont…) • Voltage source Device that can generate a prescribe voltage at its terminal. Direction current is out of +ve terminal

10. Resistance (R) • Define = convert electrical energy to another form of energy • Resistance of any material with a uniform cross-sectional area is determined by following factor: - material - length - cross-sectional area - temperature • Unit = Ohm (Ω)

11. Resistance (R) (Cont…) R = resistance (Ω) ρ = resistivity (Ω-CM) l = length (CM) A = area (CM2)

12. Insulator • Define = material that have very few free electrons and required a large applied potential (voltage) to establish a measurable current level. • Material that have high resistance to current flow • Example : paper, wood, plastic, glass, mica and etc

13. Conductor • Define = material that permit a generous flow of electrons with very little external forces (voltage) applied. • Example : copper, aluminum, silver, iron, gold and etc • Superconductivity : Material has no resistance

14. Active Element • Active element : elements capable of generating electrical energy. • Example : voltage source, current source, power supply, battery Voltage Current

15. Passive Element • Passive element : elements are not capable of generating electrical energy. • Example : resistor, capacitor, inductor

16. Resistor (R) • Component used in circuit to control the current • Unit : Ohm (Ω) • Type of resistor : - Fixed resistor - Variable resistor • Fixed resistor : are made of metal film, high resistance wire or carbon composition

17. Resistor (R) (Cont…) • Variable resistor : have a terminal resistance that can be varied by tuning a dial, knob, screw or anything else appropriate for the application.

18. Capacitor (C) • Constructed simply of two parallel conducting plates separated by insulating material (air). • Unit : Farad (F) • A capacitor has capacitance of 1 farad if 1 coulomb of charge is deposited on the plates by a potential difference of 1 volt across the plates.

19. Inductor (L) • Electrical component that opposes any change in electrical current. • Composed of coil or wire wound around a non-magnetic core/magnetic core • Unit : Henry (H) • Its behavior based on phenomenon associated with magnetic field, which the source is current.