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JAMB Physics 2003 Question 39

Question 39

Conduction through Liquids and Gases

In the calibration of an ammeter using Faraday's laws of electrolysis, the ammeter reading is kept constant at 1.20A. If 0.990g of copper is deposited in 40 minutes, the correction to be applied to the ammeter is [e.c.e. of copper = 3.3 × 10−4gC−1]

  1. A.0.03A
  2. B.0.04A
  3. C.0.05A
  4. D.0.06A
Show the answer and explanation

Answer: C (0.05A)

Explanation

m = zIt: 0.990 = 3.3 × 10−4 × I × 2400, so the true current I = 1.25 A. Correction = 1.25 − 1.20 = +0.05 A.