True or false ohm's law asserts that the current in a conducting wire is proportional to the resistance of the wire?

Answer 1

It's true, but only for a constant applied voltage. It turns out that the current in that wire is also proportional to the voltage applied to the circuit. Here's how it works.

For a given applied voltage, current is (inversely) proportional to resistance. More resistance (for that same applied voltage) makes for less current will flow. Less resistance (for that same applied voltage) means more current will flow. We say that current and resistance are proportional because for a given voltage, when one goes up by "X" amount, the other goes down by the same proportion. Double the resistance, current is cut in half. Ten times the resistance will allow only one tenth the current. And we say inversely, because the change is in the "other" direction. When current goes up, resistance must have gone down (for that same applied voltage). Here's the other half of the idea with current and voltage and a given value of resistance.

In a circuit with a fixed resistance, more voltage will drive more current. Less voltage will drive less current. They're directly proportional. That means if you double the voltage, you'll get double the current (through the same resistor). If you cut the voltage by a factor or ten (one tenth the applied voltage), you'll end up reducing current by a factor of ten (one tenth the current) for that same resistor. We usually think of circuits this way, but we can also think of them in other ways according to Ohm's law. Let's summarize.

Voltage (E) is expressed in volts (V), and current (I) is expressed in amps (A), and resistance (R) is expressed in ohms (upper case omega).

E = I x R (E equals I times R)

R = E / I (R equals E divided by I)

I = E / R (I equals E divided by R)

AnswerFalse. Ohm's Law, in essence, states that the ratio of voltage to current is constant for variations in voltage. No mention of resistance whatsoever! However, for those materials that obey Ohm's Law ('linear' or 'ohmic'), raising a conductor's resistance will cause the current to fall (assuming the voltage is fixed). so the current must be INVERSELY proportional (not proportional) to the resistance!