Chapter 4

Calculators for Electricity and Electronics

Introduction

• This chapter covers the following topics:• Types of calculators• Calculator requirements for electricity and

electronics• Using the calculator for electricity and

electronics

Types of Calculators

• Scientific calculators– Include formulas and functions used in

trigonometry and statistics• Graphing calculators

– Display graphs– Programmable

Figure 4-1 Examples of graphing calculators from the more popular calculator manufacturers. © 2014 Cengage Learning. 

Types of Calculators (cont’d.)

• Criteria for calculator selection :• Cost• Documentation• Durability• Ease of Use• Features• Support

Figure 4-4 One of Texas Instruments’ graphing calculators, which can interface with the computer. © 2014 Cengage Learning. 

Types of Calculators (cont’d.)

• Reverse polish notation (RPN)– Convenient method to enter formulas as

algebraic equations– Uses “stacks”– Easy to implement and very fast

• Scientific calculators– Used to solve physics, math, and engineering

problems

Calculator Requirements for Electricity and Electronics

• Calculator functions are most useful for this book– Plus, minus, times, divided by, inverse,

square, and square root• Know the sequence for entering data into

calculator

Calculator Requirements for Electronics (cont’d.)

• Use the proper keystroke sequence to apply a formula

• Store and recall values in memory• Calculate using exponents, reciprocals,

powers, and roots• Determine trigonometric functions of a

given phase relationship

Using the Calculator for Electricity and Electronics

• Must understand mathematical principles:– To correctly enter data– To obtain correct answer

• Example 1: addition– Problem: add 39,857 and 19,733– Solution: enter 39857, then press +, then

19733, then press =

Using the Calculator for Electronics (cont’d.)

• Example 2: subtraction– Problem: subtract 15,249 from 30,102– Solution: enter 30102, then press -, then

15249, then press =• Example 3: multiplication

– Problem: multiply 33,545 by 981– Solution: enter 33545, then press X, then 981,

then press =

Using the Calculator for Electronics (cont’d.)

• Example 4: division– Problem: divide 36,980 by 43– Solution: enter 36980, then press ÷, then 43,

then press =• Example 5: square root

– Problem: find the square root of 35,721– Solution: enter 35721, then press √

Total Resistance(Parallel Circuit)

• To calculate total resistance of a parallel circuit:– Compute the reciprocal of each branch– Take the reciprocal of the branch total

• Parallel circuit equation

Total Resistance (cont’d.)• Example 6: Calculate the total equivalent

resistance of the parallel circuit on page 38 of text

Total Resistance (cont’d.)• Example 6 solution :• Take reciprocal of R1: Enter 15, press 1/X

• Display shows 0.0666667• Take reciprocal of R2: Enter 27, press 1/X

• Display shows 0.037037• Take reciprocal of R3: Enter 33, press 1/X

• Display shows 0.030303• Take reciprocal of R4: Enter 47, press 1/X

• Display shows 0.0212766

Total Resistance (cont’d.)• Example 6 solution (cont’d.)• Add 0.0666667 and 0.037037 and

0.030303 and 0.0212766• Total equals 0.1552833• Take reciprocal of 0.1552833• Answer is 6.4398425• Round answer to 6.44 Ω

Total Resistance (cont’d.)

• Calculator with memory function allows solving without re-entering values– See Example 7 in the text for process

Rounding

• Rounding is not a calculator function– Must be done manually

• Drop the least significant digits until the desired number of digits remains

• Rounding rules– If number is less than five, the new least

significant digit is not changed

Rounding (cont’d.)

• Rounding rules (cont’d.)• If number is greater than five, increase the

new significant digit by one• If highest significant digit dropped equals

five:– Increase the new significant digit if it is odd– Do not change the new significant digit if it is

even

Rounding (cont’d.)

• Example 8: round 352.580• To the nearest tenth: 352.6• To the nearest whole number: 352• To the nearest hundred: 400