Flashcards in Calorimetry And Heat Transfer. Deck (15):

1

## What is the formula of q when temperature changes without change in state ?

### Q= msΔ#

2

## What is the formula for q when state changes without change in temperature ?

### Q=mL, when state changes without change in temperature.

3

## What is meant by specific heat of a substance s?

### Specific heat of a substance s is the heat required to increase the temperature of unit mass by 1 C or 1K

4

## What is the heat capacity of the body ?

### Heat capacity of a body= ms= heat required to increase the temperature of whole body by 1 C or 1K

5

## What is latent heat of a substance ?

### Latent hey of a substance L is the heat required to convert unit mass of the substance from one state to another state.

6

## What is meant by water equivalent of a vessel ?

### Water equivalent of a vessel of the mass equivalent of water which takes same amount of heat as taken by the vessel for same rise of temperature.

7

## What is absorptive power a ?

###
Absorptive power a = energy absorbed / energy incident.

a

8

## What is spectral absorptive power aλ?

###
Spectral absorptive power aλ= Absoptive power of wavelength λ.

aλ

9

## What is emissive power e ?

### Emissive power e is the energy radiate per unit area per unit time. It's SI units are joule per second per metre square.

10

## What is Stephans Law?

###
Emissive power of a body is given by e= e(r)σT⁴Αt.

A= Surface Area. t= time.

11

## What is Kirchhoff's Law?

###
If different bodies (including a perfectly black body) are kept at same temperature then,

e(λ)/a(λ)=constant.

12

## What are the two conclusions that can be drawn from Kirchhoff law?

###
1. Good absorbers are good emitters ( for a particular wavelength ).

2. Ratio (λ)/a(λ)=constant, at any given temperature. This ratio is equal to e(λ) of a perfectly black body at that temperature.

13

## What is the formula of weins displacement law ?

###
λ(m)T=b

b=Weins constant= 2.89 x 10^-3. Further area of graph of e(λ) vs λ will give total emissive power which is proportional to T⁴.

14

## What is Newtons Law of cooling?

### Newtons law of cooling states that if temperature difference of a body with atmosphere is small, then rate of cooling is directly proportional to temperature difference.

15