a. In physics, Ohm's law says that current through a wire, $I$, is directly proportional to voltage, $v$ , and inversely proportional to resistance,$I$ : \[I=\frac{V}{R}.\]

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?

b. All members of our painting team paint at the same rate. If $20$ members can paint a $4800$ square foot wall in $36$ minutes, then how long would it take for $9$ members to paint a $4200$ square foot wall, in minutes?

Guest Apr 21, 2020

edited by
Guest
Apr 21, 2020

#1**+1 **

This has been asked before

First voltage is not passed THROUGH a wire....voltage is applied ACROSS a wire ...current goes THROUGH a wire.

V = IR 50 = .2 R R = 250 ohms

Cut the wire in half and resistance is cut in half 125 ohms

300v = I (125) I = 2.4 amperes

b. 4800 ft^{2}/ 20p x 36 min = 6.6667 ft^{2 }/ p -min

4200 ft^{2 } / 6.6667 ft^{2}/p-min / 9p = 70 min

ElectricPavlov Apr 21, 2020