Question

In physics, Ohm's law says that current through a wire, $I$, is directly proportional to voltage, $V$, and inversely proportional to resistance, $R$: \[I=\frac{V}{R}.\]It's also true that resistance is directly proportional to the length of the wire. We have a piece of wire. We pass $50$ volts through this wire and measure $200$ milliamps of current. If I cut the wire in half and pass $300$ volts through it, how many milliamps of current will I measure?

Answer 1

2400 milliamps

Explanation:

I = v/r and I is directly porpotional to V and Inversely porporitonal to R. it also says that I is 200 and v is 50 so right now the equation would be 200 = 50/R. So right now that would be 1/4 because 200 * 1/4 = 50. Now we Have 200 = 50/ 1/4. So if we cut the wire in half which means that R will now be 1/8, and V will be 300. The equation now looks like this, I = 300/ 1/8. 300 / 1/8 is really just 300*8/1 which is 2400.

2400 = 300/ 1/8

Answer 2

I =2.4 A

Explanation:

Ohms law

I = V/R

50 V and 200 mA

The resistance is

200 * 10 ^-3 = 50/ R

R = 50 / 200 ^10^-3

R = 250

The resistance is directly proportional to the length of the wire

R = k * l where k is the constant and l is the length

250 = k * l

k = 250 / l

Now we cut the wire in 1/2 so the length is 1/2 l

R = 250/l * 1/2 l

R = 125

Back to Ohms law

I = V/R

I = 300 / 125

I =2.4 A