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Unit 7 Electric Circuits - Current Electricity

Unit 7 Electric Circuits - Current Electricity. the rate at which charge passes a point. Current I is _____________________________________________. Ex. 22 C of charge pass a point in 4.0 seconds. Find I. I =. Units: 1 coulomb/second = 1 _______________ 1 C/s = 1 ____

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Unit 7 Electric Circuits - Current Electricity

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  1. Unit 7 Electric Circuits - Current Electricity

  2. the rate at which charge passes a point Current I is _____________________________________________ Ex. 22 C of charge pass a point in 4.0 seconds. Find I. I = Units: 1 coulomb/second = 1 _______________ 1 C/s = 1 ____ So the answer can be written I = ________

  3. Physics Reference Tables, page 3: top

  4. the rate at which charge passes a point Current I is _____________________________________________ I = Δq / t Ex. 22 C of charge pass a point in 4.0 seconds. Find I. Δq / t I = = 22 C / 4.0 s = 5.5 C/s Units: 1 coulomb/second = 1 _______________ 1 C/s = 1 ____ So the answer can be written I = ________ ampere A 5.5 A

  5. fundamental A Amperes are ______________________ units. (m___sk) Coulombs are ______________________ units What is a coulomb written in terms of fundamental units? derived 1 C = = A·s Ex. How much charge passes a point if the current at the point is __________ ampere for ________seconds? 0.25 3.6 I = Δq / t Δq / 3.6 s 0.25 A = 0.90 A·s = Δq 0.90 C = Δq

  6. Don't forget that the amount of charge Dq passing a point can be written with units of __________________ or __________________________________ . The conversion from one unit to the other is found on pg 1 of PhysRT: 1 C = _______________________ e or 1 e = ________________________ C coulombs, C elementary charges, e Ex. How many electrons pass a point in 2.5 seconds if the current at that point is 0.50 A?

  7. Page 1: top

  8. Don't forget that the amount of charge Dq passing a point can be written with units of __________________ or __________________________________ . The conversion from one unit to the other is found on pg 1 of PhysRT: 1 C = _______________________ e or 1 e = ________________________ C coulombs, C elementary charges, e 6.25 x 1018 1.60 x 10-19 Ex. How many electrons pass a point in 2.5 seconds if the current at that point is 0.50 A? I = Δq / t Δq / 2.5 s 0.50 A = 1.25 C = Δq 6.25 x 1018 e 1 C 7.8 x 1018 1.25 C x ---------------------- = e

  9. at least To have current, you need _________________ 2 things. A potential difference a voltage • ___________________________ (aka ___________ source) neg. (-) _________side or _______ potential cell pos. (+) a/ a ______: _________side or _______ potential low high wire wire two _________________ different metals voltage The amount of ____________ depends on the metals used. more than 1 b/ a battery = _______________cell: more voltage more cells  _________________ generator c/ a ______________ :

  10. Physics Reference Table: page 3 bottom left:

  11. energy A voltage source V supplies ____________ to a circuit by setting up ___________________________ within the circuit. an electric field low _______ pot. high _______ pot. - + V flow of ___________ charge flow of ________ ( ) positive electrons magnified wire cross section e- negative "-" Electrons flow out of the ________________ side of V. This is equivalent to flow of ___ charge out of ___ side of V. The e-'s collide with _____________ of wire. This absorbs electrical __________________ and ______________ the wire. The speed of e-'s ______________ collisions is ____________, but the drift (________________) velocity of e- is __________ . + + atoms energy heats up fast between slow . or average

  12. "direct" Batteries supply a constant V  _____________ current  _______ DC I charge moves in ___________________ 1 direction only t Generators supply a varying V  ________________ current  ______ alternating AC I one direction charge moves in _________________ t other direction charge moves in __________________ DC In Regents Physics, we will mostly study _____ , but the basic ideas are also valid for ______. AC

  13. Edison tried to prove that AC was more dangerous than DC by electrocuting animals. Later, he helped develop the electric chair. 1903 Topsy dies.

  14. William Kemmler murdered his common law wife Tillie with a hatchet. “Chaired” on August 6, 1890

  15. Sizzlin' Sally, Old Smokey, Old Sparky, Yellow Mama, and Gruesome Gertie.

  16. complete 2. A ________________ circuit Using circuit symbols: battery Ex: V - + wire switch light open no Switch up  ___________ circuit  ________ current "complete" Close the switch  ____________ circuit  _____________  __________ flows  ______________ closed current charge Can you have voltage without current? Can you have current without voltage? yes no

  17. A Current I is measured with an _________________, which is often part of a DMM (______________________________ ). Its symbol is: ammeter digital multimeter A wire wire In an electrical circuit, ammeters are connected __________________ . This means the circuit must be ________________ and the _______________ must be _____________ into it: "in series" ammeter opened up inserted Circuit _________ ammeter: w/o with Circuit _______ ammeter: circuit part 1 circuit part 1 circuit part 2 circuit part 3 circuit part 2 circuit part 3

  18. DMM

  19. V Voltage V is measured with a _________________, which is often part of a _________. Its symbol is: voltmeter DMM V In an electrical circuit, voltmeters are connected __________________ . This means the circuit is _______ opened up , but the _______________ must be connected _____________ two points in the circuit: NOT "in parallel" voltmeter across Circuit: circuit part 1 circuit part 1 circuit part 2 circuit part 3 circuit part 2 circuit part 3

  20. V A Ammeters measure the current that passes ___________ a part of the circuit, in other words, the amount of ___________ each second that passes ____________ it. Voltmeters measure the ____________________________ from one side of a part of the circuit to the other side. This is called the voltage _____________ the circuit part. It represents the ____________ or _____________ needed to force each ________________ of charge through. through charge through potential difference "across" energy work coulomb in parallel In symbols: I circuit part in series pot. diff. affect the Ideally, neither ammeter nor voltmeters ______________ ________________________________ , but in reality they do. circuit in which they are placed

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