A body is said to be opaque to the radiation if (a, $r$ and $t$ are coefficient of absorption, reflection…

A body is said to be opaque to the radiation if (a, $r$ and $t$ are coefficient of absorption, reflection and transmission respectively)
  1. $\mathrm{t}=0$ and $\mathrm{a}+\mathrm{r}=1$
  2. $\mathrm{a}=\mathrm{r}=\mathrm{t}$
  3. $t \neq 0$
  4. $\mathrm{a}=0, \mathrm{r}=1, \mathrm{t}=1$

Solution

Opaque body does not transmit any radiation directly, $\begin{array}{ll} \therefore & \mathrm{t}=0 \\ \therefore & \mathrm{a}+\mathrm{r}=1 \end{array}$ :

Asked in: MHT CET 2023 (14 May Shift 1)

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