Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 68 of 127
Which part of the electromagnetic spectrum is emitted by warm objects and is commonly known as thermal radiation?
A
Infrared rays
B
Ultraviolet rays
C
X-rays
D
Radio waves
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Infrared rays
Concept:

According to Wien's displacement law, objects at terrestrial temperatures (\(\approx 300\text{ K}\)) emit radiation with peak intensity in the infrared spectrum.

Formula / Reaction:

$$\lambda_{\text{max}} T = b \approx 2.898 \times 10^{-3}\text{ m}\cdot\text{K}$$

Solution:

  • Thermal agitation of atoms and molecules produces radiation in the infrared band (\(700\text{ nm to }1\text{ mm}\)).


Why other options are incorrect:

  • Opt_B: Emitted by very hot bodies (stars) and atomic transitions.


  • Opt_C: Produced by inner-shell atomic transitions or decelerating high-energy electrons.


  • Opt_D: Emitted by macroscopic oscillating LC circuits.

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