Question

Assertion (A): Thermal radiations are electromagnetic radiation with wave lengths greater than visible light.
Reason (R): Thermal radiations can propagate through vacuum.

• A. both A and R are true and the R is correct explanation of the A
• B. both A and R are true, but R is not correct explanation of the A
• C. A is true, but the R is false.
• D. A is false, but the R is true.

Answer 1

The correct option is B both A and R are true, but R is not correct explanation of the A

Thermal radiations are infrared waves. They have wavelengths more that the visible rays because all the waves in infrared zone have the wavelength more than that of visible light.
Since thermal radiation are infrared waves, they follow that properties of light. So, they can propagate through vacuum.
Now, assertion and reason are both correct, but reason does not explain assertion.