Question

*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.

Answer 1

Ohm's law: I=V/R

Answer 2

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

Answer 3

For number one, I=0.5 and V=100

Answer 4

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

Answer 5

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

Answer 6

yup

Answer 7

so, 50a=x?

Answer 8

no. A is a unit.

Answer 9

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

Answer 10

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

Answer 11

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

Do you follow?

Answer 12

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

Answer 13

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.

Answer 14

ok, so its really C=V/R?

Answer 15

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

Answer 16

ok

Answer 17

(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

Answer 18

ok

Answer 19

so 0.5=100/R

Answer 20

yes.

Answer 21

now where do i go from there?

Answer 22

Multiply both sides by R.

Answer 23

so,0.5R=100?

Answer 24

Yup.

Answer 25

ok, so
divide by .5?

Answer 26

R=100/0.5
R=200

Answer 27

Yes.

Answer 28

Can you do number 2?

Answer 29

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?

Answer 30

btw, the units for the resistance are in ohms.

Answer 31

no, power is P=IV x.x

Answer 32

sorry they are different formulas.

Answer 33

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?

Answer 34

100 watts

Answer 35

ok

Answer 36

Do you need help with the rest?