Question

When a wire is heated, the current goes down from 0.3A to 0.26A. State how the resistance of the wire has changed

Answer 1

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Answer:

The resistance of the wire after being heated is approximately 1.15 times the resistance before being heated.

Step-by-step explanation:

The resistance of the wire goes up as the temperature goes up.

By Ohm's law, we have the relationship between the resistance of a conductor R, the current flowing through it, I, and the voltage across it, V,

`V=R~x~I`

As described, the current through the wire decreases so, to maintain the same voltage, the resistance must increase when the wire is heated. Let's say R1 is the resistance before heating the wire and R2 is the resistance after,

`V=R_(1) x~I_(1) =R_(2)~} x~I_(2)`

Let's solve for R2,

`R_(2) =(I_(1) )/(I_(2) )~x~R_(1)`

In this case, I1 = 0.3A and I2 = 0.26A,

`R_(2) =(0.3A)/(0.26A) ~x~R_(1) =1.15R_(1)`

Hence, the resistance of the wire after being heated is approximately 1.15 times the resistance before being heated.