Field Intensity: an 800-KHz Radio Signal Is Detected at a Point

question 22

Multiple Choice

Field intensity: An 800-kHz radio signal is detected at a point 2.7 km distant from a transmitter tower. The electric field amplitude of the signal at that point is 0.36 V/m. Assume that the signal power is radiated uniformly in all directions and that radio waves incident upon the ground are completely absorbed. What is the intensity of the radio signal at that point? (c = 3.00 × 10⁸ m/s, μ₀ = 4π × 10^-7 T ∙ m/A, ε₀ = 8.85 × 10^-12 C²/N ∙ m²)

• A) 170 µW/m²
• B) 240 µW/m²
• C) 340 µW/m²
• D) 120 µW/m²
• E) 86 µW/m²

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Definitions:

Social Exchange Theory

A theory suggesting that human relationships are formed by the use of a subjective cost-benefit analysis and the comparison of alternatives.

Altruistic Behavior

Action taken to benefit others without expecting personal gains, driven by selfless concern for the well-being of others.

Reciprocity Norms

Social norms that dictate that we should treat others as they treat us, leading to mutual benefit or support.

Reciprocity Norm

A social expectation that people will respond to each other in kind, returning benefits for benefits and responding to harms with either retaliation or forgiveness.