Physics

Problem

Four materials P, Q, R and S have thermal conductivities

0.04\,\text{W m}^{-1}\text{K}^{-1}

0.12\,\text{W m}^{-1}\text{K}^{-1}

0.80\,\text{W m}^{-1}\text{K}^{-1}

and

1.50\,\text{W m}^{-1}\text{K}^{-1}

respectively. When used in equal thickness, their order from best insulator to worst insulator is a)

S, R, Q, P

Q, P, R, S

P, Q, R, S

P, R, Q, S