zeig_101
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1) If the current in a wire is at 0.5 A and the voltage is measured at 100 volts, what is the resistance in the wire?
2)What is the electric power used by an appliance if the current is 2 A and the voltage is 50 volts?
3)How are sound waves produced, and what impacts do different types of matter have on the speed of the wave?
4)What is the electromagnetic spectrum? Explain and give an example.
5)
http://img254.imageshack.us/img254/6528/459431120201182932am187.png
In the figure shown, how could you determine the wavelength?
6)Explain how you can quickly determine whether a string of lights is wired in series or in parallel.
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inkyvoyd
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Ohm's law: I=V/R
zeig_101
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See, I dont know how to use Ohm's law
inkyvoyd
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For number one, I=0.5 and V=100
inkyvoyd
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so you just back substitute the numbers in: (0.5)=100/R
Next you isolate R.
0.5R=100
R=200
zeig_101
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ok, so,
.5 A=100V/X?
inkyvoyd
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yup
zeig_101
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so, 50a=x?
inkyvoyd
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no. A is a unit.
inkyvoyd
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It's not a variable. If it helps you, use Amps instead of A
zeig_101
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Ok, I don't get this can you walk me through it?
inkyvoyd
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Okay. We know that I=V/R.
We also know that I=0.5Amps and V=100Volts
Do you follow?
zeig_101
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What do the things in I=V/r mean?
inkyvoyd
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It's a relationship between current, voltage, and resistance. I is a variable that represents current. V is a variable that represents voltage. R is a variable that represents resistance. We usually give these measurements in Amperes (A), Volts (V) and Ohms (omega), respectively.
zeig_101
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ok, so its really C=V/R?
inkyvoyd
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We don't use C for current. We use I. This is out of habit, so use I okay?
zeig_101
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ok
inkyvoyd
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(In mathematics we often encounter constants and we represent them with C's. If we used C for current it would be confused with other values and would not be clear). BUt essentially yes, the relationship is I=V/R
zeig_101
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ok
zeig_101
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so 0.5=100/R
inkyvoyd
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yes.
zeig_101
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now where do i go from there?
inkyvoyd
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Multiply both sides by R.
zeig_101
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so,0.5R=100?
inkyvoyd
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Yup.
zeig_101
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ok, so
divide by .5?
zeig_101
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R=100/0.5
R=200
inkyvoyd
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Yes.
inkyvoyd
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Can you do number 2?
zeig_101
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What is the electric power used by an appliance if the current is 2 A and the voltage is 50 volts?
I=V/r
2=50/r
2r=50
r=100?
inkyvoyd
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btw, the units for the resistance are in ohms.
inkyvoyd
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no, power is P=IV x.x
inkyvoyd
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sorry they are different formulas.
zeig_101
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What is the electric power used by an appliance if the current is 2 A and the voltage is 50 volts?
P=I*V?
P=2A*50V
P=100?
inkyvoyd
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100 watts
zeig_101
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ok
inkyvoyd
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Do you need help with the rest?