Fill in the blanks:
$(a)$ $0.49 \frac{\text{cal}}{\text{cm} \cdot \text{K} \cdot \text{s}} = \dots \frac{\text{J}}{\text{m} \cdot \text{K} \cdot \text{s}}$
$(b)$ If the rate of emission of heat of a substance is less than its rate of absorption,then its temperature $\dots$.
$(c)$ The rate of emission of heat of a substance is directly proportional to $\dots$ of temperature of it and surroundings.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Given $1 \text{ cal} = 4.184 \text{ J}$ and $1 \text{ cm} = 10^{-2} \text{ m}$.
$0.49 \frac{\text{cal}}{\text{cm} \cdot \text{K} \cdot \text{s}} = 0.49 \times \frac{4.184 \text{ J}}{10^{-2} \text{ m} \cdot \text{K} \cdot \text{s}} = 0.49 \times 418.4 \approx 205 \frac{\text{J}}{\text{m} \cdot \text{K} \cdot \text{s}}$.
Note: If using $1 \text{ cal} = 4.2 \text{ J}$,then $0.49 \times 420 = 205.8 \approx 206$.
$(b)$ If the rate of absorption is greater than the rate of emission,the substance gains net energy,so its temperature will increase.
$(c)$ According to Newton's Law of Cooling,the rate of loss of heat is directly proportional to the difference in temperature between the body and its surroundings,provided the difference is small.

Explore More

Similar Questions

Determine whether the following statements are True or False:
$(a)$ "Conduction stops once a rod achieves thermal steady state."
$(b)$ $A$ surface that is a good emitter is also a good absorber.
$(c)$ $A$ perfect black body must be black in color.
$(d)$ The value of heat capacity is the same under different conditions for a given matter.

Statement $A$: Convection involves flow of matter within a fluid due to unequal temperatures of its parts.
Statement $B$: $A$ hot bar placed under a running tap water loses heat due to the effect of convection within water.
Statement $C$: Heat transfer always involves a temperature difference between two systems.

$A$ heated body emits radiation which has maximum intensity at frequency $f_m$. If the temperature of the body is doubled,then:

Difficult
View Solution

Heat loss takes place from a body maintained at a temperature of $400^{\circ} C$ to the surrounding air at $30^{\circ} C$ by convection and to the surrounding surfaces at $30^{\circ} C$ by radiation. The Newton's cooling coefficient is $20 \ W / m^2 \ K$ and the Stefan-Boltzmann constant is $5.67 \times 10^{-8} \ W / m^2 \ K^4$. If the rate of heat loss by convection is equal to the rate of heat loss by radiation,the emissivity of the body surface is

In Column-$I$,system surroundings and in Column-$II$ modes of heat transfer are given below. Match the following:
Column-$I$ Column-$II$
$(a)$ Cup of hot tea in room $(i)$ Forced convection
$(b)$ Substance kept near fire $(ii)$ Natural convection
$(iii)$ Conduction
$(iv)$ Radiation

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo