Read the following statements : A . When small temperature difference between a liquid and its surrounding is doubled the rate of loss of heat of the liquid becomes twice. B . Two bodies P and Q having equal surface areas are maintained at temperature 10 ° C and 20 ° C . The thermal radiation emitted in a given time by P and Q are in the ratio 1 : 1 . 15 C . A carnot Engine working between 100 K and 400 K h

Step-by-step solution

A . by Newton's law of cooling - d θ d t ∝ Δ θ B . According to Stephan's law d H d t = σ e A T 4 ⇒ H P H Q = T P T Q 4 = 283 293 4 ⇒ H P : H Q = 1 1 . 03 4 = 1 : 1 . 03 4 = 1 : 1 . 15 ⇒ B is correct C . The efficiency of the Carnot cycle is given by η = 1 - T 1 T 2 = 1 - 100 400 = 3 4 = 75 % D . is wrong as according to the Newton's law of cooling d θ d t ∝ Δ T