Two slabs `A` and `B` of equal surface area are placed one over the other such that their surfaces are completely in contact. The thickness of slab `A` is twice that of `B`. The coefficient of thermal conductivity of slab `B` is maintained at `25^(@)C`. The temperature at the contact of their surface is

Options

A. `62.5^(@)C`
B. `45^(@)C`
C. `55^(@)C`
D. `85^(@)C`

Explanation

To solve the problem, we need to determine the temperature at the contact surface of the two slabs A and B. Here's a step-by-step breakdown of the solution:

### Step 1: Define the parameters
- Let the thickness of slab B be \( L \).
- Therefore, the thickness of slab A, which is twice that of slab B, will be \( 2L \).
- Let the coefficient of thermal conductivity of slab B be \( K \). Thus, the coefficient of thermal conductivity of slab A will be \( 2K \).
- The temperature at the surface of slab A is maintained at \( 100^\circ C \), and the temperature at the surface of slab B is maintained at \( 25^\circ C \).

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