Understanding Opaque Medium Radiation Interaction

When radiation interacts with a medium, it can be absorbed ($A$), reflected ($R$), or transmitted ($T$). For any medium, the sum of these components must equal the incident radiation ($I$):

$I = A + R + T$

The problem states the medium is "completely opaque". This implies that no radiation can pass through it. Therefore:

$T = 0\%$

Calculating Reflection

We are given that 50% of the incident monochromatic radiation is absorbed:

$A = 50\%$

Using the conservation equation:

$100\% = A + R + T$

Substitute the known values:

$100\% = 50\% + R + 0\%$

Solving for the reflection ($R$):

$R = 100\% - 50\% - 0\% = 50\%$

Evaluating the Statements

Now, let's evaluate each statement based on our findings ($A=50\%$, $R=50\%$, $T=0\%$):

• P. 50% of the incident radiation is reflected: This is CORRECT because we calculated $R = 50\%$.
• Q. 50% of the incident radiation is reflected: This is identical to statement P and is also CORRECT.
• R. 25% of the incident radiation is transmitted: This is INCORRECT. Since the medium is opaque, transmission ($T$) must be $0\%$.
• S. No incident radiation is transmitted: This is CORRECT. This aligns with the definition of an opaque medium ($T = 0\%$).

Determining the Correct Option

The question asks which statements are CORRECT. Statements P, Q, and S are correct based on the analysis. However, we need to choose the option that combines these correctly.

Option 1 combines statements P and S. Both P (50% reflected) and S (No transmission) are correct findings.

Therefore, the correct combination is P and S only.