Calculate the electric current required to deposit 0.972 g of chromium in three hours. ECE of chromium is 0.00018 gC⁻¹.

JAMB Physics 2024 68 views

Calculate the electric current required to deposit 0.972 g of chromium in three hours. ECE of chromium is 0.00018 gC⁻¹.

  1. 0.75 A
  2. 0.50 A ✓
  3. 0.83 A
  4. 0.17 A

Explanation

Direct variation: y ∝ x means y = kx (k is constant). When x doubles, y doubles. Example: distance = speed × time. Inverse variation: y ∝ 1/x means y = k/x. When x doubles, y halves.

Joint variation: z varies with multiple variables. z ∝ xy means z = kxy. Partial variation combines direct variation with a constant: y = kx + c.

Finding k: substitute known values. If y = 12 when x = 4 in direct variation: 12 = k(4), so k = 3. Then y = 3x. Use this to find unknown values. Show units to verify logic.

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