Lect01 Electrical Quantities and Laws Electrical Eng for Mech 802307

8/9/2019 Lect01 Electrical Quantities and Laws Electrical Eng for Mech 802307

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802307

ELECTRICAL ENGINEERING FORMECHANICAL ENGINEER

Tarek M. Abdolkader


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• Description of

the

course

• Fundamental electrical quantities and laws

لعربية لسعوديلمملكة

جامعة م لقر-وز رة لتعليم لعالي

كلية لهندسة و لعمارة إلسالمية

قسم لهندسة لكهربائية

802307: ELECTRICAL ENGINEERING

FOR MECHANICAL ENGINEER

K INGDOM OF SAUDI ARABIA

Ministry of Higher Education

Umm Al-Qura University

College of Engineering and Islamic ArchitectureElectrical Engineering Department

Lecture

1


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21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 3

OUTLINE

• Description of the course• Course outline

• Notices

• Grading policy

• Do we need Electrical Engineering?

• Fundamental

electrical

quantities

and

laws• Charge• Current

• Voltage

• Power

and

energy


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Presentation slides: (not adequate alone)

Lecture notes

Textbook:

John Bird, Electrical and Electronic principles and Technology , 2nd Ed., Newnes,

2003.

References:

1. Hughes, “Electrical technology,” 7th Ed., Addison‐Wesley, 1995.

2. A.E. Fitzgerald,

“Basic

electrical

engineering,”

McGraw

‐Hill.

3. T. A.DeMassa,“Electrical and Electronic Devices Circuits and Instruments,” West

Publishing Company, St. Paul, 1989.

4. P.J. Freeman, “Electric power transmission and distribution,” 2nd Ed., Harrap

Resources


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1. Attendance of lectures is a must.

2. Ask whenever you feel any ambiguity or confusion.

3. You have to read the text book along with lecture notes and presentation slides.

4. Solving a lot

of

examples

and

exercises

is

a must

to

get

the

skills

needed

to

pass

this

course.

لنصيح لنصيحلين لنصيحلين لنصيحلين لنصيحلين لنصيحلين لنصيحلين لنصيحلين لنصيحلين لين

Notices


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Semester works

40

Attendence

5

0.5 grades are subtracted for each one hour

absence in either lecture or Lab. Absence

more than 25% of hours of the course

(lecture and/or Lab) leads to Denial.Homeworks (HWs)

10

HWs given in lecture are due before the next

lecture. To take the grades of HW, you must

come to office hours to discuss solution with

the instructor.

Quizzes

10

Two Quizzes are given with 5 grades each.

The first Quiz is after the 4rd week and thesecond Quiz is after the 10th week

Midterm

15

Midterm exam should be after the 7 th week

Lab

20

Lab semester work

10

For each experiment, a report to be

submitted

Final lab exam

10

After the 13th week.

Final exam

40 No curve up

Semester works 40%

Lab 20%Final Exam 40%

Grading Policy


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You need Electrical Engineering


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You need Electrical Engineering


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Charge


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Current


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Current

A constant current (also known

as a direct current or DC) is

denoted by symbol I whereas a

time-varying current (alsoknown as alternating current or

AC) is represented by the

symbol i or i(t )


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If a current of 5 A flows for 2 minutes, find the quantityof electricity transferred.

See Problem 1 at p. 4 in the textbook

Q

= 600 C


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The total charge passing through a conductor is given by:

5 sin(4 )q t t mC π =

Calculate the

electric

current

at

t =

0.5

s


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Determine the total charge entering a terminal between t = 1 sand t = 2 s if the current passing the terminal is defined by:

i = (3

t 2

– t

) A


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Voltage


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VoltageMathematically,

ab

dwv

dq

=

Where v is in volts (V), w is energy in joules (J), and q is charge in Coulombs

(C)

1 volt = 1 joule/coulomb

Like electric current, a constant voltage is called a DC voltage and it is

represented by V, whereas a sinusoidal time-varying voltage is called a AC

voltage and is represented by v. The electromotive force (e.m.f) provided by a

source of energy such as a battery (DC voltage) or an electric generator (ACvoltage) is measured in volts


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Power and Energy


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Power and EnergyWe write the relationship as:

dw p

dt =

Where p is the power in Watts, w is the energy in joules (J), and time in

seconds. From voltage and current equations, it follows that:

dw dw dq p vi

dt dq dt = = =

p is the

instantaneous

power

and

is

equal

to

the

product

of

instantaneous

voltage and current


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• Due to the conservation of energy,

The algebraic sum of power in a circuit, at any instant of time, must be zero

0 p =∑• In another form,

The total power supplied = the total power absorbed

The supplied by the source = VI

The power absorbed by the resistor = VI

Power and Energy


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A source of e.m.f of 5 V supplies a current 3 A for 10 minutes.How much energy is provided in this time?


Energy = 9 kJ


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An electric heater consumes 1.8 MJ when connected to a 250 Vsupply for 30 minutes. Find the power rating of the heater andthe current taken from the supply.


Power = 1 kW

Current = 4 A


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An air conditioner of 3 kW power. How does it cost per month tooperate this AC 10 hours per day. 1kwh costs 10 Halalah.

Lect01 Electrical Quantities and Laws Electrical Eng for Mech 802307

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