## zeig_101 2 years ago *reward: 1 medal for answers* 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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1. inkyvoyd

Ohm's law: I=V/R

2. zeig_101

See, I dont know how to use Ohm's law

3. inkyvoyd

For number one, I=0.5 and V=100

4. inkyvoyd

so you just back substitute the numbers in: (0.5)=100/R Next you isolate R. 0.5R=100 R=200

5. zeig_101

ok, so, .5 A=100V/X?

6. inkyvoyd

yup

7. zeig_101

so, 50a=x?

8. inkyvoyd

no. A is a unit.

9. inkyvoyd

It's not a variable. If it helps you, use Amps instead of A

10. zeig_101

Ok, I don't get this can you walk me through it?

11. inkyvoyd

Okay. We know that I=V/R. We also know that I=0.5Amps and V=100Volts Do you follow?

12. zeig_101

What do the things in I=V/r mean?

13. inkyvoyd

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.

14. zeig_101

ok, so its really C=V/R?

15. inkyvoyd

We don't use C for current. We use I. This is out of habit, so use I okay?

16. zeig_101

ok

17. inkyvoyd

(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

18. zeig_101

ok

19. zeig_101

so 0.5=100/R

20. inkyvoyd

yes.

21. zeig_101

now where do i go from there?

22. inkyvoyd

Multiply both sides by R.

23. zeig_101

so,0.5R=100?

24. inkyvoyd

Yup.

25. zeig_101

ok, so divide by .5?

26. zeig_101

R=100/0.5 R=200

27. inkyvoyd

Yes.

28. inkyvoyd

Can you do number 2?

29. zeig_101

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?

30. inkyvoyd

btw, the units for the resistance are in ohms.

31. inkyvoyd

no, power is P=IV x.x

32. inkyvoyd

sorry they are different formulas.

33. zeig_101

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?

34. inkyvoyd

100 watts

35. zeig_101

ok

36. inkyvoyd

Do you need help with the rest?