A thermal conductivity meter (see Figure) is used to measure the thermal conductivity of a solid material. Two identical samples of the tested material are used. Electrical energy supplied to the electric resistance heater of the device is at a rate of 40 W. Measurement of temperature difference between two points in the sample separated by a distance L 2cm is measured to be 20 °C. The diameter of the tested sample is 4 cm. The thermal conductivity of the tested sample is about ???: had Sample Theple Sample 0.02 W/(m.K) 15.9 W/(m.K) 12.2 W/(m.K) ⋅ Coding fluid