WAEC - Physics (1993 - No. 50)
What amount of current would pass through a 10 Ω coil if it takes 21s for the coil to just melt a lump of ice of mass 10g at 0oC if there are no heat losses? (Latent heat of fusion of ice = 336 Jg\(^{-1}\)).
16.00A
4.00 A
0.50A
0.25A
0.06 A
Explanation
I\(^2\)Rt = mI;
I = \(\sqrt{\frac{mI}{Rt}}\)
= \(\sqrt{\frac{10 \times 336}{10 \times 21}}\)
= \(\sqrt{16}\)
= 4.0A
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