When the temperature difference between the junctions of a given thermocouple is $120^{\circ}C$ , the thermo emf is 30 m V. The temperature of hot junction is decreased by $20^{\circ}C$ and cold junction is increased by $6^{\circ}C$ . The percentage decrease in thermo emf is ( assume thermo emf is directly proportional to the temperature difference)

Question

$\begin {array} {1 1} (1)\;43 & \quad (2)\;2.16 \\ (3)\;20.4 & \quad (4)\;21.6 \end {array}$