Physics Chapter on Radiation and Heat Transfer

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Questions and Answers

If the specific heats of two substances are in the ratio of 3:2, what is the temperature of the mixture when equal masses of the two substances are mixed?

36°C

29°C

24°C

32°C (correct)

What is the relationship between the cooling time intervals T₁, T₂, and T₃ when a body cools from 80°C to 50°C?

T₁ < T₂ < T₃ (correct)

T₁ > T₂ > T₃

T₁ < T₂ > T₃

T₁ = T₂ = T₃

Given a rod of length 4 m with one end at 100°C and the other at 20°C, what is the temperature at a point C which is 2 m from the hotter end?

80°C (correct)

90°C

40°C

60°C

When a bimetallic strip with two different metals is cooled, how will it bend if the thermal coefficient of linear expansion of metal 1 is greater than that of metal 2?

Convex on side 1 Signup and view all the answers

What is the temperature at which centigrade and Fahrenheit scales agree?

-30°C Signup and view all the answers

Which of the following cannot function as a thermometric property?

Pressure of gas at constant temperature Signup and view all the answers

What is the coefficient of cubical expansion of a substance with linear thermal expansion coefficients of 4 x 10⁻⁵/°C, 5 x 10⁻⁵/°C, and 6 x 10⁻⁵/°C?

15 x 10⁻⁵ /°C Signup and view all the answers

If a block of metal's volume changes by 0.6% when heated through 10°C, what is this an example of?

Cubic expansion Signup and view all the answers

What is the coefficient of linear expansion of the metal?

4 x 10⁻⁶ /°C Signup and view all the answers

Which species shows the incorrect direction of the inductive effect?

CH₂ and C-OH Signup and view all the answers

Which method is used to detect Boron?

Ca method Signup and view all the answers

Which of the following free radicals is considered the most stable?

(CH₃)₃C. Signup and view all the answers

Which meristem is primarily responsible for increasing the girth of a plant?

Lateral meristem Signup and view all the answers

What shape does a typical growth curve in plants exhibit?

Sigmoid Signup and view all the answers

In the geometric growth equation, what does 'e' represent?

Base of natural logarithm Signup and view all the answers

Which hormone is involved in apical dominance and xylem differentiation?

Auxin Signup and view all the answers

What will be the absorptance of a body if its reflectance and transmittance are 0.4 and 0.3 respectively?

0.5 Signup and view all the answers

What is the temperature on the W scale that corresponds to 39°C on the Celsius scale, given freezing and boiling points of water are 39°W and 239°W?

139°W Signup and view all the answers

Which of the following correctly states the value of 0°C on the Kelvin scale?

273.15 K Signup and view all the answers

If a spherical black body emits radiation with power P at temperature T, what will be the power emitted by another black body of the same material, double the radius, and half the temperature?

1/8 P Signup and view all the answers

What is the water equivalent of a body that has a heat capacity of 40 cal/°C?

40 g Signup and view all the answers

What will be the final temperature when mixing equal masses of two liquids A at 40°C and B at 20°C?

30°C Signup and view all the answers

Which term best describes the process when a cell undergoes a change from a specialized state back to a less specialized state?

Dedifferentiation Signup and view all the answers

In plant growth, what is the phase characterized by rapid increase in size and biomass?

Exponential phase Signup and view all the answers

Which synthetic auxin is incorrectly identified among the following options?

2,4,5-T Signup and view all the answers

Which feature is not characteristic of arithmetic growth?

Presence of a stationary phase Signup and view all the answers

What will happen when the apical bud of a plant is removed?

More lateral branches will be seen Signup and view all the answers

Which type of cell wall develops in tracheary elements?

Lignosic Signup and view all the answers

Which of the following plants does not exhibit different leaf shapes at juvenile and mature stages?

Coriander Signup and view all the answers

What is the measurement used to describe the growth of a pollen tube?

Length Signup and view all the answers

Which phylum is recognized as the second largest in the animal kingdom?

Mollusca Signup and view all the answers

Which of the following features is absent in organisms of phylum Annelida?

Jointed appendages Signup and view all the answers

Study Notes

Physics

The absorptance of a body is the ratio of the amount of radiation absorbed to the amount of radiation incident on it.
If the reflectance and transmittance of a body are 0.4 and 0.3 respectively, the absorptance is 0.3 because the sum of reflectance, transmittance, and absorptance must equal 1.
The temperature on the W scale corresponding to 39°C on the Celsius scale is 139°W. This is determined by the linear relationship between the two scales, where the freezing point of water is 39°W and the boiling point is 239°W.
The correct value of 0°C on the Kelvin scale is 273.15 K.
The power of radiation emitted by a black body is proportional to the fourth power of its temperature and the square of its surface area. So, a black body with double the radius and half the temperature has a power of 1/8 P.
Water equivalent is the mass of water that would absorb the same amount of heat as the body. The water equivalent of a body is calculated by dividing its heat capacity by the specific heat of water (1 cal/g°C).
When mixing liquids with different specific heats, the final temperature of the mixture is determined by the specific heats and the initial temperatures of each liquid.
Newton's Law of Cooling states that the rate of cooling of an object is proportional to the temperature difference between the object and its surroundings. This explains why the cooling time decreases as the temperature difference decreases.
Thermal conductivity is the ability of a material to conduct heat energy. Copper has a higher thermal conductivity than steel, making it more efficient for heat transfer in cooking pans.
The heat capacity of a sphere is proportional to its volume, which is proportional to the cube of its radius. So, the ratio of heat capacities of two spheres with radii in the ratio 1:3 is 1:27.
A bimetallic strip bends when cooled due to the difference in thermal expansion coefficients of the two metals. The metal with the higher coefficient of linear expansion will contract more, causing the strip to bend towards the side of the metal with the lower expansion coefficient.
The temperature at which the Celsius and Fahrenheit scales give the same reading is -40°C or 233.15 K.
Thermometric properties are properties of a substance that change with temperature. While pressure, volume, and resistance can be used as thermometric properties, pressure at constant temperature does not change with temperature and cannot be used.
Cubical expansion is the expansion of a material in three dimensions. The coefficient of cubical expansion is approximately three times the coefficient of linear expansion.
The coefficient of linear expansion is a measure of how much a material expands per degree Celsius. It can be calculated using the formula: ΔL/L = αΔT, where ΔL is the change in length, L is the original length, α is the coefficient of linear expansion, and ΔT is the change in temperature.

Chemistry

Inductive effect is the transmission of electron density through σ bonds. In the incorrect direction, the electron density is withdrawn from the carbon atom adjacent to the substituent, making them slightly more positive.
The Carius method is used to detect halogens (Cl, Br, I) in an organic compound. This method involves heating the organic compound with fuming nitric acid in the presence of silver nitrate. The halogen is converted to a silver halide, which is precipitated.
The stability of a free radical is determined by factors such as hyperconjugation, resonance, and inductive effects:
- Tertiary free radicals (like (CH₃)₃C.* ) are more stable due to greater hyperconjugation.
Metamers are structural isomers that have the same molecular formula but different arrangements of alkyl groups on either side of a functional group.

Botany

Lateral meristems, like the vascular cambium and cork cambium, are responsible for increasing the girth of the plant.
The typical growth curve in plants is sigmoid, characterized by an initial lag phase, followed by a rapid growth phase, and finally a plateau phase.
Arithmetic growth occurs when a constant amount of growth is added per unit time. This is seen in root elongation.
In the formula for geometric growth, 'e' represents the base of the natural logarithm, which is approximately 2.718.
Gibberellins are plant hormones that promote stem elongation, seed germination, and fruit development.
GA₃ is the most intensively studied form of gibberellins.
Auxins play a crucial role in apical dominance, which is the suppression of lateral bud growth by the apical bud. Auxins also promote xylem differentiation.
Cytokinins stimulate cell division, while gibberellins promote cell elongation. Together, they can improve the shape of apples and increase the length of grape stalks.
During cell elongation, increased vacuolation is observed, allowing for greater cell expansion.
Growth is an irreversible increase in size and volume, accompanied by metabolic processes. In living organisms, growth typically occurs from inside. Growth continues in plants throughout their lifespan; however, in animals, growth is mostly limited to a specific age period.
Synthetic auxins like 2, 4-D, IBA, and NAA are used in agriculture for various purposes. 2,4,5-T is a synthetic auxin, but it has been banned due to its environmental effects.
Arithmetic growth is characterized by constant growth rate, linear growth curve, and its absence in a stationary phase. It is commonly seen in root meristems.
When the apical bud is removed, the suppression of lateral buds by auxin is removed, leading to the growth of more lateral branches.
Tracheary elements are specialized cells in xylem that transport water. Their secondary cell wall is lignified for strength and elasticity, making them robust and resilient.
Some plants display different leaf shapes at the juvenile stage compared to the mature stage. This phenomenon is not observed in cotton.
The growth of a pollen tube is measured by its length, as this indicates the rate of its elongation towards the ovule.

Zoology

Arthropoda is the second largest phylum in the animal kingdom, after Mollusca.
Annelida, the phylum that includes earthworms, is characterized by metamerism (segmentation), nephridia (excretory organs), and parapodia (fleshy lobes for locomotion). Unlike arthropods, annelids do not have jointed appendages.
Sea cucumbers belong to the phylum Echinodermata. They are triploblastic and coelomate, meaning they have a three-layered body plan and a true body cavity. They possess a water vascular system for movement and feeding. While they are classified as marine animals, they undergo external fertilization
Molluscs have a mantle cavity that houses gills for respiration. The shape and structure of gills vary among different mollusc groups, including feather-like, filament-like, chambered, and bag-like gills.
In most molluscs, the digestive system is complete with the mouth on the ventral side and the anus on the dorsal side.
Open circulatory systems are characteristic of organisms like cockroaches, where blood flows through open spaces and not through a closed circulatory system.
Statocysts are sensory organs in crustaceans like prawns. They are responsible for balance by detecting changes in orientation.
Antedon is a member of the crinoid group within Echinodermata, commonly known as sea lilies.
Balanoglossus is a hemichordate with a cylindrical body divided into three regions: proboscis, collar, and trunk.
In Balanoglossus, the proboscis gland plays a key role in excretion.
Molluscs are triploblastic, meaning they have three germ layers in embryonic development. They are also unsegmented and bilaterally symmetrical.
Hirudinaria, a type of leech, is characterized by having a triploblastic and coelomate body, bilateral symmetry, and nephridia for excretion. It is not acoelomate.
Chitinous exoskeletons are crucial to survival on land for arthropods, providing structural support and protection.
Earthworms (Pheretima) and cockroaches (Periplaneta) share the common feature of having a segmented body.

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Description

This quiz covers key concepts of radiation, absorptance, and the temperature scales in physics. It includes questions on reflectance, transmittance, and the properties of black bodies. Test your understanding of these fundamental topics in thermal physics.