The voltage across the rheostat is 20V and its resistance is 5 ohms. Determine the amount of heat
| September 14, 2021 | education
The voltage across the rheostat is 20V and its resistance is 5 ohms. Determine the amount of heat released in the rheostat in 20 minutes?
The amount of heat that is released in the rheostat can be calculated from the Joule-Lenz law:
Q = (U ^ 2 / R) * t.
According to the conditions of the problem:
U = 20 (V), R = 5 (Ohm), t = 20 (min).
Let’s translate the time from minutes to seconds t = 20 (min) = 20 * 60 (s) = 1200 (s) = 1.2 * 103 (s).
Substitute the obtained values into the Joule-Lenz law:
Q = (U ^ 2 / R) * t = (20 ^ 2/5) * 1.2 * 10 ^ 3 = 80 * 1.2 * 10 ^ 3 = 96 * 10 ^ 3 = 9.6 * 10 ^ 4 (c).
Answer: Q = 9.6 * 10 ^ 4 (s).
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