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Joule's law describes how electricity can turn into heat during its passage through a conductor, which in this case is the human body. When electrical current flows, it experiences resistance. This leads to heat being generated. The law is mathematically represented by the formula \( Q = I^{2}Rt \). Here:

• \( Q \) is the heat energy produced, measured in Joules.
• \( I \) is the current flowing through the conductor, measured in Amperes.
• \( R \) is the resistance in the path of the current, measured in Ohms.
• \( t \) is the time duration for which the current flows, measured in seconds.

In the example of a lightning strike, the body acts as a conductor with a specific resistance. As a result, when the lightning strikes, a large amount of heat is generated in a very short time due to the high current of 25,000 A passing through the body with given resistance. This concept is crucial to understanding the thermal effects of electrical current on conductors, in this case, a human body.

Specific heat capacity is a property of a substance that describes how much heat energy is required to change its temperature. It's usually denoted by \( c \), with units of Joules per kilogram per degree Celsius (\( J/kg°C \)).For water, the specific heat capacity is quite high at \( 4.18 \times 10^{3} \ J/kg°C \). This means water absorbs a lot of heat before its temperature increases significantly. Hence, it's used as a reference in many thermal calculations.In the context of the lightning strike problem, knowing the specific heat capacity of water is essential as it helps us calculate how much the temperature of the water-like body mass will rise when a specific amount of heat is transferred to it. The formula for this calculation is \( \Delta T = \frac{Q}{mc} \), where:

• \( \Delta T \) is the change in temperature.
• \( Q \) is the heat energy subjected to the mass, in Joules.
• \( m \) represents the mass of the water, in kilograms.

Without knowing the specific heat capacity, we would not be able to predict the temperature change resulting from the energy transferred by the lightning strike.

Heat transfer is the process where heat energy moves from one substance, object, or region to another. It can occur through conduction, convection, or radiation. In the case of a lightning strike, heat transfer primarily occurs through conduction and the body's distribution of heat. When the heat is generated by a lightning strike, it does not stay confined to the point of contact. Instead, it spreads throughout the body. This is crucial for minimizing localized damage by "diluting" the heat, potentially saving the body from more severe burns. Moreover, rapid heat transfer in a body ensures that, while there might be an immediate increase in temperature at the point of strike, this heat is quickly spread out, reducing the intensity at any single point. However, even if the person were to survive the initial strike, the rapid heat can lead to severe internal damage and burns, reflecting why the temperature might not rise as expected.

Resistance is a measure of how much a material opposes the flow of electrical current. For humans, resistance varies based on conditions. In dry conditions, the body's resistance is relatively high. However, in wet conditions, such as in rain, the resistance decreases significantly.When wet, the outer layer of the skin becomes highly conductive, leading to potentially dangerous scenarios during events, like lightning strikes. In the provided exercise, the resistance is set at \( 1.0 \ k\Omega \), a typical assumption for a wet body.Lower resistance means that a greater portion of the current can flow through the body, as per Ohm's Law and Joule’s law, leading to more heat being produced internally. This significantly heightens the risk during a lightning strike, as more heat can mean more severe thermal injuries. Understanding resistance is key to assessing the possible outcomes and damage from such extreme electrical exposure.