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Grade 8


Module 15

Important measuring units

Activity 1

To be able to explain the most important measuring units and their mutual connection

LO 2.4

We have already said that an electrical current is the flow of electrons in a circle. The speed at which the electrons flow, is measured in Ampère. In order to measure amperage, one must allow the current to flow through an Ammeter.

The battery supplies the energy that is also called the electromotive force (EMF ). It is measured in Volts . In order to measure voltage one must place the two points of a voltmeter on either side of a component.

Resistance is offered against the flow of the current and the resistance is measured in Ohms .

A battery does not provide its full energy because some of its energy is lost. This is called power and it is measured in Watts .

Ohm’s law states that the current through a resistor is directly proportional to the tension that is coupled over a resistor, i.e. the current is directly proportional to the tension and inversely proportional to the resistor. It is formulated as follows:

I = V / R

Actuation is the energy that must supply the battery and is wasted as heat in a resistor. It is formulated as follows:

P = V x I

  • Summary of electrical units
Symbol Unit Abbreviation

The formulas make it possible for one to determine units through mathematical computations, e.g. if one has the Volts and Ampère of a circuit, one can calculate the power. Nowadays we use advanced apparatus to measure current, tension and resistance.

  • The multimeter is such a device. If your school owns one, you will have the opportunity to take readings with it.

Assignment 1

1. Provide two more formulas that can be derived from the formula I = V / R.

2. Provide two more formulas that can be derived from the formula P = V x I.

LO 2.4


Learning outcomes(LOs)
LO 2
TECHNOLOGICAL KNOWLEDGE AND UNDERSTANDING The learner will be able to understand and apply relevant technological knowledge ethically and responsibly.
This is demonstrated when the learner:
structures:2.1 demonstrate knowledge and understanding of frame structures:
  • the use and application of basic structural components (columns, beams, arches, buttresses, struts, stays, guys, ties);
  • reinforcing techniques for frame structures (triangulation, webs and fillets, orientation and cross-sectional area and members);
  • how frame structures can be made strong (e.g. relationship between the size and the shape of the base, the centre of gravity and stability;
systems and control:2.4 demonstrates knowledge and understanding of how electrical circuits with more than one input or control device will work based on different logic conditions (“AND” and “OR” logic), and represents them using circuit diagrams, systems diagrams and truth tables.


  • The following definitions are important:
  • Electric current: Flow of electrons in a closed circuit
  • Voltage: Electromotive force that enables the flow of electric current
  • Resistance: Quality of materials offering resistance to the flow of electric current.
  • Power: The energy that a battery has to provide and which is used in a resistor.

Ohm's law:

  • This states that the current passing through a resistor is directly proportional to the potential difference, or voltage, across the resistor, i.e. the current is directly proportional to the linked voltage and inversely proportional to the resistance.

Assignment 1

1. V = I × R and R = V/I

2. V = P/I en I = P/V

3. R = V/I = 3 1,5 size 12{ { {3} over {1,5} } } {} = 2 ohm

4. P = V × I = 3V × 1,5A = 4,5 watt

Questions & Answers

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Damian Reply
absolutely yes
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Akash Reply
it is a goid question and i want to know the answer as well
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Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
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Mostly, they use nano carbon for electronics and for materials to be strengthened.
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s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
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s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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Sanket Reply
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Damian Reply
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abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
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Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
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Source:  OpenStax, Technology grade 8. OpenStax CNX. Sep 13, 2009 Download for free at http://cnx.org/content/col11052/1.1
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