An electric heater is used to maintain a temperature of `15^@C` inside a room of total wall area 125 m". The outside temperature is `-10^@C` . The walls of the room are made of three different layers, innermost layer is made of wood of thickness 2 cm, middle layer is made of brick of thickness 20 cm and outermost layer is made of cement of thickness 2 cm. If there is no loss of heat through the floor and ceiling, find the power of heater. Take, thermal conductivities of wood, brick and cement as `0.125 Wm^(-1) ""^@C^(-1) , 1.0 Wm^(-1) ""^@C^(-1) " and " 1.5 Wm^(-1) ""^@C^(-1)` , respectively.

Explanation

To find the power of the heater required to maintain the temperature inside the room at \(15^\circ C\) when the outside temperature is \(-10^\circ C\), we will use the concept of thermal conductivity and the formula for heat transfer through multiple layers of materials.

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Inside temperature, \(T_{inside} = 15^\circ C\)
- Outside temperature, \(T_{outside} = -10^\circ C\)
- Total wall area, \(A = 125 \, m^2\)
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