Question

The material used in the manufacturing of cooker must have (K-coefficient of thermal conductivity, S- specific heat of material used):
A) High K and low S
B) Low K and low S
C) High K and high S
D) Low K and high S

Answer 1

Hint: To reach the answer, think about what is the property which makes a cooker so usable? They do not absorb much heat while they transfer heat from inside to outside and not actually needing high amounts of heat to reach at the right and needed temperature. Since it needs to absorb less heat and conduct or transfer more heat, you can decide whether the values of K should be higher or lower.

Complete step by step answer:
As explained in the hint section of the solution to the asked question, to reach at the answer, we need to think about what is the property of a cooker that makes it so easy to use and efficient to cook with. A good and efficient cooker absorbs the least possible amount of heat while being able to transfer or conduct heat to the outside as much as possible. Now that we know what an efficient cooker needs, we now need to check which coefficient out of K and S is the one we need to be higher and which one is needed to be lower.
K is given to be coefficient of thermal conductivity, which signifies the ability of a material or substance to conduct heat or transfer the heat from one side to another, quickly and more efficiently. Since the cooker needs to do the same, it needs to have a high value for K.

S is given to be the specific heat of the material used, which signifies the heat that is needed to bring about a change in the temperature of the material or the object manufactured using that material. Since, the cooker is supposed to intake less amount of heat to reach at the right temperature value, the value of S should be low.

Now, we can safely say that for a cooker to be efficient and better working, the value of K should be high and the value of S should be low, which matches with the option (A).

Hence, option (A) is the correct answer.

Note: The key point in solving the question is to know what K (coefficient of thermal conductivity) and S (specific heat of the material) actually mean. Many students mess up their meanings and thus reach at a totally incorrect answer, which is usually the opposite of the right answer, i.e. low K and high S.