Physics 5054 · O Level · Resistance

Resistance — practice question

A student studies how the resistance changes for different lengths $l$ of a metal wire PQ, which has a total length of $1.000\,\text{m}$.
(a(i))[1]

Observe the voltmeter scale and enter your result in Table 3.1.

(a(ii))[1]

Calculate the resistance of a section of wire of length $l = 10.0\,\text{cm}$ using $R = \frac{V}{I}$. Record your answer in Table 3.1.

(b)[2]

The student repeats the method for lengths $l = 20.0\,\text{cm}$ and $l = 40.0\,\text{cm}$ of wire and notes her results in Table 3.1. Study the values in Table 3.1. Allowing for experimental error, suggest the relationship between $l$ and $R$.

(c)[1]

The student notices that the wire is warm at the end of the investigation. Describe one precaution that the student can take to reduce this heating effect.

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