MR2003 Elektronika Industri

Laboratorium Sistem Produksi

MR2003

Elektronika Industri

Pendahuluan

Performance Objective



Definition of electricity



Ways of generating electricity



Factors that determine resistance



Types of circuits



State Ohm’s law



Ways of measuring electricity



Identify the switches used to control electricity



Read a resistor color code

2

What is electricity?



Current electricity

 Flow of electrons along a conductor

 +/- charges form an electric field of forces within atom

 Electrons and proton attract each other and tend to hold electrons in orbit

 The ability of electrons to move or flow is the basis of current electricity

What is electricity?

 Atom structure

4

Conductors & Insulators

Conductors

6

Conductivity of materials



Conductors

 Material through which electrons move

 A material that has many free electrons tends to be a good conductor

 Copper is preferred because strength and cost



Insulators

 Substances that restricts flow of electrons

 Ex: wood, glass, mica etc



Semiconductors

 A material having a good conductivity and a good insulator

Conductivity of materials

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Material Resistivity ρ (Ωm)

Temperature coefficient

Silver 1.59×10⁻⁸ 0.0038

Copper 1.68×10⁻⁸ 0.003862

Gold 2.44×10⁻⁸ 0.0034

Aluminium 2.82×10⁻⁸ 0.0039

Germanium 4.60×10⁻¹ −0.048

Silicon 6.40×102 −0.075

Wood 1.00×10³to 1.00×10⁴ Glass 1.00×10¹¹ to 1.00×10¹⁵

Air 1.30×10¹⁴to 3.30×10¹⁴

PET 1.00×10²¹

Teflon 1.00×10²³to 1.00×10²⁵

Resistance



Opposition of movements of electrons along a conductor

 Generate heat

 Control electron flow

 Supply correct voltage to a device



Factors

 Material: number of free electrons

 Length: longer has more resistance

 Cross-sectional area (wire size): larger area has less resistance

 Temperature: higher temperature has more resistance

Semiconductors

10

Semiconductors

Current flows from negative potential to positive potential and is assisted by free electrons when voltage is applied to N-type material

Semiconductors

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When voltage is applied to P-type

material, the holes are filled with free

electrons that move from the negative

potential to the positive potential through the crystal

Diodes

In a diode, P-type and N-type materials exchange carriers at the junction of the two materials, creating a thin depletion region.

Diodes

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Energy



Energy is capacity to do work



The sources of energy used to produce

electricity are coal (46%), nuclear power (20%), natural gas (20%), oil (1%), other (wind, solar, water, etc. ≈ 13%)



Electricity is converted into: rotary motion by

electric motors (62%), light (20%), and for heat,

linear motion, sound, visual outputs (18%)

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Voltage



Voltage is the amount of electrical pressure in a circuit, also known as electromotive force (EMF) or potential difference



Voltage is either direct current (DC) or alternating current (AC).

 DC voltage is voltage that flows in one direction only

 AC voltage is voltage that reverses its direction of flow at regular intervals

Voltage

Production

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Voltage is produced by

electromagnetism, heat, light, chemical reaction, pressure, and friction.

Generating electricity



Pressure

 Electricity is produced when certain pressure is

applied to certain crystals (Rochelle salts or quartz)

Generating electricity



Heat

 Electricity is produced when heat is applied to the junction between two dissimilar metals

20

Generating electricity



Light

 Electricity is

produced when light strikes a photosensitive material

Generating electricity



Chemical Action

 Electricity is

produced when a chemical

action takes place between two metals in a cell

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Generating electricity



Magnetism

 Electricity is produced when a magnet is moved past a piece of wire or a piece of wire is moved through a

magnetic field

AC Voltage

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AC voltage has one positive alternation and one negative alternation per cycle and is either single-phase (1ϕ) or three-phase (3ϕ).

DC Voltage

DC voltage is produced from batteries, photovoltaic cells, and rectified AC voltage supplies and can vary from almost pure DC voltage to half- wave DC voltage.

Ohm’s law & Power

 The strength of the current (I) is directly proportional to the voltage (E) and inversely proportional to the resistance (R)

 I = E / R

 Power (P) is defined as the rate at which work is done (watt)

 P = E x I

 P = E² / R

 P = I² x R

 In metric measurement, it is expressed in watts for power and joules (J) for energy or work (1 W = 1 J/s)

 Electric motors are still rated in horsepower (1 hp = 746 W)

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Circuits

A. simple, B. series, C. parallel, D. series-parallel

Series Connection

28

Water Analogy

Parallel Connection

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Cell and Battery Current

Circuits (2)



Open circuit



Short circuit

A short circuit usually generate an excess of

current flow which results overheating (causing fire)

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Measuring Electricity (1)

 Current flow through a coil, a magnetic field is setup

 The magnetic field determines how far the coil will be deflected

Measuring Electricity (2)

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Multimeter Digital multimeter AC clamp-on meter

Controlling electricity



Switches

Knife Switch

Toggle Switch

Controlling electricity



Resistors

 Device used to provide a definite required amount of opposition to current in a circuit

36

Controlling electricity



Resistors

 Color code

Controlling electricity

a. Berapakah nilai hambatan kedua resistor berikut:

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b. Kedua resistor tersebut dihubungkan secara paralel dengan resistor 100 kilo-ohm. Diketahui bahwa arus yang mengalir melalui resistor 100 kilo-ohm adalah 30 mA. Berapakah arus yang mengalir melalui kedua resistor yang lain?

c. Ketiga resistor dihubungkan secara seri. Berapakah arus yang mengalir melalui masing-masing resistor?