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A student plans to find the resistance of a nichrome wire with two different methods. The first method involves measuring the wire’s length ($l$) and diameter ($d$), then referencing the resistivity $\rho $ of nichrome.

The student uses $R=\cfrac { \rho l }{ \pi { (\frac { d }{ 2 } ) }^{ 2 } }$ to calculate the nichrome wire’s resistance.

The second method involves using alligator clips to connect the nichrome wire into a circuit with a 1.5-volt D-cell battery.

The student inserts an ammeter into the circuit to measure current $I$ and uses $R=\frac { \Delta V }{ I }$ to calculate the resistance.

The student wishes to conduct the second method properly. Of the choices below, which are the two most important actions to control in the experiment?

Select TWO answers.

A

Make sure the nichrome wire is as straight as possible, not having any curves to it.

B

Collect the measurements quickly so that the nichrome wire does not have time to increase in temperature.

C

Set the nichrome on a hard metallic surface to ensure good conduction while taking measurements.

D

Connect the alligator clips to the very ends of the nichrome wire, not at points near the middle of the wire.

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