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ERIE COMMUNITY COLLEGE TITLE III Metric Conversions Project Interdisciplinary Course Materials For Technology

Course: MT 001 (Pre-Algebra) or MT 003 (Pre-Algebra Review)

Course Outline Topics:

 Perform fundamental operations (addition, subtraction, multiplication, division) with real numbers.  Demonstrate a sense of numbers by determining if a mathematical solution is “reasonable”.  Present organized written work.  Read critically and think logically when solving application problems.  Demonstrate an understanding of order of operations to complete calculations on a scientific calculator.

Project Title: Metric Conversions used in Electronics

Project Description:

Students will convert units commonly used in electronics applications from one metric unit to another.

Author: Lynette Meslinsky, Mathematics/Computer Science

Curriculum Expert: Robert Gannon, Automotive Technology

Semester Created: Fall 2009

A. Essential Question

How do I use a decimal point conversion table to convert from one decimal unit to another? What do the various symbols used in metric measurement mean mathematically? How do I apply these conversions and measurements in electronics problems?

B. Introduction:

Current is measured in amperes (amp or A) or in fractions of an ampere called milli-amps or micro-amps. Amps are related to watts or volts by the following formulas:

1. volts to amps: amps=watts/volts 2. amps to volts: volts=watts/amps 3. watts = volts x amps

Erie Community College Title III Grant In this project you will explore converting from one metric unit of amps, volts or watts to another. You will become familiar with the symbols used to represent these units in metric measurement. Finally you will attempt to answer some questions posted on line which apply these concepts.

C. Things to Learn Before Starting the Project

The diagram below shows the units most commonly used in electronics that are associated with the metric system.

Example:

1 Mv = 1 megavolt = 1,000,000 volts 1 Kv = 1 kilo volt = 1,000 volts 1 mv = 1 millivolt = .001 volts 1 µv = 1 microvolt = .000001 volts

The table is designed to show you how to convert from one unit to another by moving the decimal point 3 places as indicated by the arrows. i.e.

To change from Mv to KV move the decimal point 3 places to the right. To change from Mv to mv move the decimal point 9 places to the right. To change from mv to Kv, move the decimal point 6 places to the left. To change from µv to Mv, move the decimal point 12 places to the left.

Examples:

.000012 Mv = .012 Kv = 12 v = 12,000 mv = 12,000,000 µv 180,000 µA = 180 mA = .18 A = .00018 KA = .00000018 MA

DECIMAL POSITION CHART 3 3 3 3 BASE M K UNITS m µ Mega Kilo Volts Milli Micro 1,000,000 1,000 Amps .001 .000001 Watts 3 3 3 3

Erie Community College Title III Grant D & E.Directions & Project Assignment:

1. The following 2 examples were given in the project introduction. Write out each example using words to replace notation symbols.

Examples 1: .000012 Mv = .012 Kv = 12 v = 12,000 mv = 12,000,000 µv

Words:

Example 2: 180,000 µA = 180 mA = .18 A = .00018 KA = .00000018 MA

Words:

2. Practice using the conversion table to complete the following exercises:

a) 10 A = ______µA

b) .00005MA = ______mA

c) .003 kA = ______A

d) 2,000 mA = ______µA

e) 15 V = ______MV

f) 6,000 mv = ______V

g) 16,500 µV = ______KV

h) .96 Mv = ______mV

i) 2,000 KW = ______W

j) 3.2 MW = ______mW

Erie Community College Title III Grant 3. Now use the table and the formulas provided in the introduction to see if you can answer these questions posted on line.

a) A 60 watt car spotlight is showing a drain of 5.5 amps on the ammeter. What is the voltage?

b) Hey, what is the formula to convert milliamps to amperes? 450 mA to amperes?

c) I was wondering if anyone has general knowledge of how many decorative lights/lamps my transformer can run. I have blown up 2 tranformers in the last 2 weeks trying to run approximately 40 lights on my layout. Both the tranformers were your basic christmas light type which convert 120 volts into a 12 volt output. I think the lights each use 100 ma. What is my total amp load? What is the total wattage?

d) How do i calculate kW if i have amp?? any formula? I have a 600amps motor and the voltage is 120 V.

F. Student Resources http://www.onlineconversion.com/electric_current.htm Electric Current Conversion website

G. Faculty Resources

Students will need to have developed the procedural knowledge necessary to manipulate formulas. In addition they may need instruction in the use of the conversion table.

H. Grading Rubric

All parts should be graded on Mathematical logic used through work shown (50%) as well as accuracy (50%)

Questions 1 25% Question 2 25% Question 3 50%

Erie Community College Title III Grant