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Individual solar cells are connected electrically in modules to meet electrical-energy needs. They can be wired together in series or in parallel—connected like the batteries discussed earlier. A solar-cell array or module usually consists of between 36 and 72 cells, with a power output of 50 W to 140 W.

The output of the solar cells is direct current. For most uses in a home, AC is required, so a device called an inverter must be used to convert the DC to AC. Any extra output can then be passed on to the outside electrical grid for sale to the utility.

Take-home experiment: virtual solar cells

One can assemble a “virtual” solar cell array by using playing cards, or business or index cards, to represent a solar cell. Combinations of these cards in series and/or parallel can model the required array output. Assume each card has an output of 0.5 V and a current (under bright light) of 2 A. Using your cards, how would you arrange them to produce an output of 6 A at 3 V (18 W)?

Suppose you were told that you needed only 18 W (but no required voltage). Would you need more cards to make this arrangement?

Section summary

  • All voltage sources have two fundamental parts—a source of electrical energy that has a characteristic electromotive force (emf), and an internal resistance r size 12{r} {} .
  • The emf is the potential difference of a source when no current is flowing.
  • The numerical value of the emf depends on the source of potential difference.
  • The internal resistance r size 12{r} {} of a voltage source affects the output voltage when a current flows.
  • The voltage output of a device is called its terminal voltage V size 12{V} {} and is given by V = emf Ir size 12{V="emf" - ital "Ir"} {} , where I size 12{I} {} is the electric current and is positive when flowing away from the positive terminal of the voltage source.
  • When multiple voltage sources are in series, their internal resistances add and their emfs add algebraically.
  • Solar cells can be wired in series or parallel to provide increased voltage or current, respectively.

Conceptual questions

Is every emf a potential difference? Is every potential difference an emf? Explain.

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Explain which battery is doing the charging and which is being charged in [link] .

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The diagram shows two cells of e m f script E sub one equals twelve volts and internal resistance r sub one equals one ohm, and e m f script E sub two equals eighteen volts and internal resistance r sub two equals zero point five ohms, connected. The cells are connected with their positive terminals facing each other in a closed circuit.

Given a battery, an assortment of resistors, and a variety of voltage and current measuring devices, describe how you would determine the internal resistance of the battery.

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Two different 12-V automobile batteries on a store shelf are rated at 600 and 850 “cold cranking amps.” Which has the smallest internal resistance?

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What are the advantages and disadvantages of connecting batteries in series? In parallel?

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Semitractor trucks use four large 12-V batteries. The starter system requires 24 V, while normal operation of the truck’s other electrical components utilizes 12 V. How could the four batteries be connected to produce 24 V? To produce 12 V? Why is 24 V better than 12 V for starting the truck’s engine (a very heavy load)?

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Problem exercises

Standard automobile batteries have six lead-acid cells in series, creating a total emf of 12.0 V. What is the emf of an individual lead-acid cell?

2.00 V

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Questions & Answers

2 how heat loss is prevented in a vacuum flask
Abdullah Reply
what is science
logical reasoning for a particular phenomenon.
I don't know anything about it 😔. I'm sorry, please forgive 😔
due to non in contact mean no conduction and no convection bec of non conducting base and walls and also their is a grape between the layer like to take the example of thermo flask
dimensions v²=u²+2at
Lagben Reply
what if time is not given in finding the average velocity?
Alan Reply
the magnetic circuit of a certain of the flux paths in each of the long and short sides being 25cm and 20cm reprectielectrove. there is an air gap of 2mm long in one the long sides if a flux density of 0.8weber/m is to produce in the magnet of 1500 turns..
Daniel Reply
How do you calculate precision
Sacky Reply
what module is that?
Chemisty 1A?
No it has something to do with measurements bro... What we did today in class
Tah bra honestly I didn't understand a thing in that class..when re your Tutorials?
Friday bro... But the topics we did are in this app... Just try to master them quickly before the test dates... Are you done with the Maths sheet
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@Fillemon Nanwaapo
lol, hush
There are very large numbers of charged particles in most objects. Why, then, don’t most objects exhibit static electricity?
Bilkisu Reply
Because there's an equal number of negative and positive charges... objects are neutral in nature
when a ball rolls on a smooth level ground,the motion of its centre is?
Mary Reply
what is electro magnetic field?
electromagnetic field is a special type of field been produced by electric charges..!!! like the word electro from Electricity and the word magnetic from Magnetism.. so it is more of a join field..!!!
Electromagnetic field is caused by moving electric charge
when a ball rolls on a smooth level ground,the motion of its centre is?
what's the relationship btw displacement and position
Declan Reply
displacement is the change of position 8======✊=D 💦💦
what is the meaning of elasticity
Pele Reply
is the ability of a material to or any object to expand to a limit point
this is about kinematics you bonk
what does emf/R mean
Eze Reply
What is work
Wisdom Reply
work is the product of force and perpendicular distance
Pls explain simple harmonic motion
Olaiya Reply
Any to and from motion of a fluid or any elastic object
a current of 5.5mA is flowing through a 3.3k resistor.compute th p.d developed across the resistor
Clifford Reply
A p.d of 24 volts exist across a 15 OHM'S resistor.calculate the current flowing the resistor
a current of 5.5mA is flowing through a 3.3kOHM'S resistor.compute th p.d developed across the resistor
solve it please
the so unit power is the watt(w)/joul/second (w1)/s
Jibo Reply
what is time
Jibo Reply
a measure of the duration of an event
Practice Key Terms 4

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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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