A soldering iron with a resistance of 400 ohms is included in a circuit with a voltage of 220 V.

A soldering iron with a resistance of 400 ohms is included in a circuit with a voltage of 220 V. How much heat will be released in a soldering iron in 10 minutes?

Given:
R = 400 Ohm;
U – 220 V;
t = 10 min.
Find: Q.
Decision:
To solve the problem, we will use the Joule – Lenz law. It is written like this: Q = I2Rt.
We do not know the value of the current strength. Therefore, we will replace it through the voltage that we know. Then the formula will look like: Q = U2t / R.
Let’s substitute the values of the variables into it and find the answer. Q = 200 * 2 * 10/400 = 36 300 J = 36.3 kJ.
Answer: 36.3 kJ