Waec Model Questions Vol1 2021 Physics Question 25

Practice objective / multiple choice question 25 from the 2021 Waec Model Questions Vol1 Physics examination.

Waec Model Questions Vol1 2021 Physics Objective / Multiple Choice Hard Difficulty
Question 25 WAEC_MODEL_QUESTIONS_VOL1 • 2021 • PHYSICS • objective

A copper wire of length 2.0 m and cross‑sectional area $1.0\,\text{mm}^2$ has a resistivity of $1.68\times10^{-8}\,\Omega\,\text{m}$ at $20^{\circ}\text{C}$. Its temperature coefficient of resistance is $0.004\,\text{°C}^{-1}$. The wire is used as a heating element and is allowed to reach $120^{\circ}\text{C}$. Determine (i) the resistance of the wire at $120^{\circ}\text{C}$, (ii) the current that will cause it to dissipate $100\,\text{W}$ at that temperature, and (iii) the voltage across the wire at that current.

Answer Options

A. R = 0.050 Ω; I = 44.7 A; V = 2.24 V
B. R = 0.048 Ω; I = 45.6 A; V = 2.19 V
C. R = 0.034 Ω; I = 54.5 A; V = 1.85 V
Correct Answer D. R = 0.047 Ω; I = 46.1 A; V = 2.17 V
Correct Answer
D
Correct Option:
R = 0.047 Ω; I = 46.1 A; V = 2.17 V

About This Question

This is Waec Model Questions Vol1 2021 Physics Question 25. It is one of the objective questions from the 2021 Waec Model Questions Vol1 Physics examination.

Difficulty level: Hard .

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