Question

Light is incident on an interface between water (refractive index \(=1.33\)) and glass (refractive index \(=1.5\)). For total internal reflection, light should be travelling from \[ (i_c \text{ is the critical angle}) \]

• A. Water to glass with an angle of incidence \(i>i_c\)
• B. Glass to water with an angle of incidence \(i>i_c\)
• C. Water to glass with an angle of incidence \(i<i_c\)
• D. Glass to water with an angle of incidence \(i<i_c\)

Hint:

Always remember: \[ \text{TIR} \Rightarrow \text{Denser Medium} \rightarrow \text{Rarer Medium} \] and \[ i>i_c \] Both conditions must be satisfied simultaneously.

Answer 1

The Correct Option is B

Concept: Total Internal Reflection (TIR) occurs only when:
• Light travels from an optically denser medium to a rarer medium.
• The angle of incidence is greater than the critical angle.

Step 1: Identify the denser medium. Given, \[ n_{\text{glass}}=1.5 \] \[ n_{\text{water}}=1.33 \] Since \[ 1.5>1.33 \] glass is optically denser than water.

Step 2: Apply the condition for total internal reflection. For TIR, light must travel from glass to water and \[ i>i_c \]

Step 3: Choose the correct option. \[ \boxed{ \begin{array}{c} \text{Light must travel from glass to water} \text{with } i>i_c. \end{array} } \] Hence, the correct option is \[ \boxed{(B)} \]