Subelement A: — Topic :
Question 6A61
Element 6 (Radiotelegraph)A 20 ohm resistor with a current of 0.25 A passing through it will dissipate how many watts?
Explanation
To determine the power dissipated by a resistor, we use the formula P = I$^2$R, where P is power in watts, I is current in amperes, and R is resistance in ohms. This fundamental relationship, often called Joule's Law, is critical in amateur radio for calculating component stress and ensuring proper circuit design.
Given:
Current (I) = 0.25 A
Resistance (R) = 20 ohms
Applying the formula:
P = (0.25 A)$^2$ * 20 ohms
P = 0.0625 A$^2$ * 20 ohms
P = 1.25 watts
Therefore, the resistor dissipates 1.25 watts. Understanding power dissipation is essential for selecting components that can handle the heat generated in a circuit, preventing damage and ensuring reliable operation. Options A, B, and C result from incorrect application of power formulas.
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