Two rods of length `d_(1)` and `d_(2)` and coefficients of thermal conductivites `K_(1)` and `K_(2)` are kept touching each other. Both have the same area of cross-section. The equivalent thermal conductivity.

Options

A. `K_(1)+K_(2)`
B. `K_(1)d_(1)+K_(2)d_(2)`
C. `(K_(2)d_(1)+K_(1)d_(2))/(d_(1)+d_(2))`
D. `(d_(1)+d_(2))/((d_(1))/(K_(1))+(d_(2))/(K_(2)))`

Explanation

To find the equivalent thermal conductivity of two rods in contact, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Parameters**:
- Let the lengths of the two rods be \(d_1\) and \(d_2\).
- Let the coefficients of thermal conductivity be \(K_1\) and \(K_2\).
- Both rods have the same cross-sectional area \(A\).
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