An 800-KHz Sinusoidal Radio Signal Is Detected at a Point

question 47

Multiple Choice

An 800-kHz sinusoidal radio signal is detected at a point 2.1 km distant from a transmitter tower.The electric field amplitude of the signal at that point is 0.80 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? (ε₀ = 8.85 × 10^-12 C²/N ∙ m²,μ₀ = 4π × 10^-7 T ∙ m/A,c = 3.0 × 10⁸ m/s)

• A)8.5 × 10^-4 W/m²
• B)1.2 × 10^-3 W/m²
• C)1.7 × 10^-3 W/m²
• D)6.0 × 10^-4 W/m²
• E)4.2 × 10^-4 W/m²

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Definitions:

Postconventional Reasoning

The highest stage in Kohlberg's theory of moral development, characterized by the ability to think abstractly and make decisions based on universal ethical principles rather than concrete rules or expectations.

Sensorimotor Stage

The first stage of Piaget's theory of cognitive development, occurring from birth to about 2 years of age, where infants learn about the world through their senses and motor activities.

Formal Operational

The stage in Piaget's theory of cognitive development where individuals gain the ability to think abstractly, reason logically, and understand hypothetical concepts.

Preoperational

A stage in Piaget's theory of cognitive development where children from 2 to 7 years old engage in symbolic play and struggle with logic.