What is the polarising angle for glass? 

Answer

To find the polarizing angle for glass, we can use Brewster's Law, which states that the polarizing angle (also known as Brewster's angle) can be calculated using the refractive index of the medium. Here's a step-by-step solution:

### Step 1: Understand Brewster's Law
Brewster's Law states that the polarizing angle (θ_B) is given by the formula:
\[ \tan(\theta_B) = \frac{n_2}{n_1} \]
where \( n_2 \) is the refractive index of the denser medium (glass) and \( n_1 \) is the refractive index of the less dense medium (air, which is approximately 1).

### Step 2: Identify the Refractive Index of Glass
For typical glass, the refractive index (n) is approximately 1.5. Therefore, we can use:
\[ n_2 = 1.5 \]
\[ n_1 = 1 \]

### Step 3: Apply Brewster's Law
Substituting the values into Brewster's Law:
\[ \tan(\theta_B) = \frac{n_2}{n_1} = \frac{1.5}{1} = 1.5 \]

### Step 4: Calculate the Polarizing Angle
To find the polarizing angle, we take the arctangent (inverse tangent) of 1.5:
\[ \theta_B = \tan^{-1}(1.5) \]

### Step 5: Use a Calculator
Using a calculator, we find:
\[ \theta_B \approx 56.3^\circ \]

### Conclusion
The polarizing angle for glass is approximately \( 56.3^\circ \).

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