Question

Practical 2(a). Using an accumulator, an ammeter, a 2 Ω resistor, a key K, a resistance wire BP, a crocodile clip J and other material: connect the circuit as shown; use the crocodile clip to hold the resistance wire at D such that BD=d=80 cm; close the key and record the ammeter reading I, then evaluate I⁻¹; repeat for d=70, 50, 40, 30 cm; tabulate the results; plot a graph of d (vertical axis) against I⁻¹ (horizontal axis); determine the slope, s, of the graph; state two precautions taken to ensure accurate results.

Accepted Answer

This is a practical experiment: for each length d of resistance wire in the circuit, the ammeter reading I is recorded and I⁻¹ computed. A graph of d against I⁻¹ is plotted (expected to be a straight line, since resistance—and hence I⁻¹—is proportional to length d), and the slope s is read from the graph. Precautions include ensuring tight, clean circuit connections and avoiding parallax error when reading the ammeter.

WAEC Physics 2021 Theory — Question 33

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