Heat and Temperature MCQ Quiz - Objective Question with Answer for Heat and Temperature - Download Free PDF

Concept:

Coefficient of Linear Expansion:

• The change in length of a metal rod due to temperature change is given by:
  • ΔL = α L₀ ΔT, where:
    • ΔL is the change in length (1.6 mm = 1.6 × 10⁻³ m),
    • L₀ is the original length (2 m),
    • α is the coefficient of linear expansion, and
    • ΔT is the change in temperature (60°C - 0°C = 60°C).
• Rearranging the formula to solve for α:
  • α = ΔL / (L₀ ΔT)

Calculation:

Given,

ΔL = 1.6 mm = 1.6 × 10⁻³ m

L₀ = 2 m

ΔT = 60°C

Using the formula for α:

α = ΔL / (L₀ ΔT)

α = (1.6 × 10⁻³) / (2 × 60) = 1.33 × 10⁻⁵ /°C

∴ The coefficient of linear expansion of the metal rod is 1.33 × 10⁻⁵ /°C. Option 1) is correct.

Concept:

Coefficient of Linear Expansion:

• The change in length of a metal rod due to temperature change is given by:
  • ΔL = α L₀ ΔT, where:
    • ΔL is the change in length (1.6 mm = 1.6 × 10⁻³ m),
    • L₀ is the original length (2 m),
    • α is the coefficient of linear expansion, and
    • ΔT is the change in temperature (60°C - 0°C = 60°C).
• Rearranging the formula to solve for α:
  • α = ΔL / (L₀ ΔT)

Calculation:

Given,

ΔL = 1.6 mm = 1.6 × 10⁻³ m

L₀ = 2 m

ΔT = 60°C

Using the formula for α:

α = ΔL / (L₀ ΔT)

α = (1.6 × 10⁻³) / (2 × 60) = 1.33 × 10⁻⁵ /°C

∴ The coefficient of linear expansion of the metal rod is 1.33 × 10⁻⁵ /°C. Option 1) is correct.

Concept:

Joule-Thomson effect: 

• The Joule-Thomson effect also known as Kelvin–Joule effect or Joule-Kelvin effect is the change in fluid’s temperature as it flows from a higher pressure region to lower pressure.
• 
• The basic principle of the Joule-Thomson effect is based on the transfer of heat.
• The cooling produced in the Joule-Thomson expansion has made it a very valuable tool in refrigeration.

Explanation:

• When a puncture happens, the air flows from the high-pressure region inside to the low-pressure region outside.
• As air gains kinetic energy, it gains this energy from the internal heat of the air.
• So it will use the internal energy of the compressed air, so it uses up internal heat and temperature falls.
• This phenomenon is referred to as, the Joule-Thomson effect.

The correct answer is Water-1200.

Key PointsSpecific Heat Capacity

• The quantity of heat (J) absorbed per unit mass (kg) of the material or substance when its temperature increases 1 K (or 1 °C).
• Its units are J/(kg K) or J/(kg °C).

Atmospheric Pressure

• The average air pressure at sea level at a temperature of 15 degrees Celsius.
• ​An atmosphere (atm) is a unit.
• 1atm = 1,013 millibars or 760 millimeters of mercury.
• Atmospheric pressure drops as altitude increases. 

Additional InformationList of some substances and Specific Heat Capacity: 

The correct answer is Calorie.

Key Point

• The concept of Calory:
  • Calorie, a unit of heat energy in the metric system.
  • The measurement of heat is called calorimetry.
  • The calorie, or gram calorie, is the quantity of heat required to raise the temperature of 1 gram of pure water 1°C.
  • The kilocalorie is used in dietetics for stating the heat content of a food, i.e., the amount of heat energy that the food can yield as it passes through the body; in this context, the kilocalorie is usually called simply the calorie.
  • The amount of heat energy needed to effect a 1°C temperature increase in 1 gram of water varies with temperature (see heat capacity); thus the temperature range over which the heating takes place must be stated to define the calorie precisely.
  • The 15° calorie, or normal calorie, is widely used in chemistry and physics; it is measured by heating a 1-gram water sample from 14.5°C to 15.5°C at 1-atmosphere pressure.
  • The 4° calorie, also called the small calorie or therm, is measured from 3.5°C to 4.5°C (water is most dense at 3.98°C); the large calorie, or Calorie, is equivalent to 1,000 small calories.
  • The average value of the calorie in the range 0°C to 100°C is called the mean calorie; it is  1⁄100 of the energy needed to heat 1 gram of water from its melting point to its boiling point.
  • The calorie may also be defined by expressing its value in some other energy units.

 Additional Information

•  Ohm
  • Ohm is denoted by symbol Ω. It is the Greek letter omega.
  • This is named after Georg Simon Ohm, a German physicist who studied the relationship between voltage, current, and resistance.
  • Resistance is the measurement of the opposition to current flow in an electrical circuit.
  • It is also defined as the ratio of the voltage applied to the electric current which flows through it.
  • The resistance of a material is directly proportional to the length and inversely proportional to the area of cross-section. It is also directly proportional to the resistivity of the material.
  • Conductors have less resistance and that is why current can flow easily through it. Insulators have high resistance and that is why current can not flow easily through it.
  • Ohm's law states that the electric current is proportional to voltage and inversely proportional to resistance. It is represented by V=IR.​
• ​Newton
  • Newton is the SI unit of force. And force equals the product of mass and acceleration.
  • SI unit of force = Newton
  • SI unit of mass = kg
  • SI unit of acceleration = m.sec-2.
  • Hence, 1 Newton is equals to, kg m.sec-2  . the other units do not satisfy the unit of Newton.

Heat is a form of energy. Heat energy can be transferred to other forms of energies. Heat flows from a hotter body to a colder body.

Units of heat:

• Calorie: It is the quantity of heat required to raise the temperature of 1 gram of water through 1°C
• Joule: It is the SI unit of Heat energy

1 Calorie = 4.186 joule

Here the heat required of 1 kg of water is being asked which will be equal to = 1000 × heat required of 1 kg of water = 1000 calorie

Hence the heat required to increase 1° Celsius temperature of one-kilogram water is 1000 calorie.

The correct answer is Water-1200.

Key PointsSpecific Heat Capacity

• The quantity of heat (J) absorbed per unit mass (kg) of the material or substance when its temperature increases 1 K (or 1 °C).
• Its units are J/(kg K) or J/(kg °C).

Atmospheric Pressure

• The average air pressure at sea level at a temperature of 15 degrees Celsius.
• ​An atmosphere (atm) is a unit.
• 1atm = 1,013 millibars or 760 millimeters of mercury.
• Atmospheric pressure drops as altitude increases. 

Additional InformationList of some substances and Specific Heat Capacity: 

The fundamental modes of heat transfer are:

• Conduction is the method of transfer of heat within a body or from one body to the other due to the transfer of heat by molecules vibrating at their mean positions. The bodies through which the heat transfers must be in contact with each other. Conduction occurs usually in solids where molecules in the structure are held together strongly by intermolecular forces of attraction amongst them and so they only vibrate about their mean positions as they receive heat energy and thus pass it to the surrounding molecules through the vibration.
• Convection is the mode of heat transfer which occurs mostly in liquids and gases. In this method, heat transfer takes place through the actual motion of matter from one place within the body to the other.
• Radiation is a form of heat transfer. It does not require any medium and can be used for transfer of heat in a vacuum as well. This method uses electromagnetic waves which transfer heat from one place to the other. 

Concept:  

The movement of energy from one place to another is called energy transfer. Heat transfer mainly takes place due to temperature differences.

There are three modes of Heat transfer.

Explanation:

The fundamental modes of heat transfer are:

Conduction

• Conduction is the method of transfer of heat within a body or from one body to the other by molecules vibrating at their mean positions.
• The bodies through which the heat transfers must be in contact with each other. 
• Conduction occurs usually in solids where molecules in the structure are held together strongly by intermolecular forces of attraction amongst them and so they only vibrate about their mean positions as they receive heat energy and thus pass it to the surrounding molecules through the vibration.

Convection:

• Convection is the mode of heat transfer which occurs mostly in liquids and gases.
• In this method, heat transfer takes place through the actual motion of matter from one place within the body to the other.

Radiation

• Radiation is a form of heat transfer.
• It does not require any medium and can be used for the transfer of heat in a vacuum as well.
• This method uses electromagnetic waves which transfer heat from one place to the other. 

• A calorimeter is used to measure the enthalpy, the heat energy, of a reaction.
• A thermometer is an instrument for measuring temperature. It usually consists of a narrow glass tube containing a thin column of a liquid which rises and falls as the temperature rises and falls.
• A pyrometer is an apparatus for measuring high temperatures that uses the radiation emitted by a hot body as a basis for measurement.
• A thermocouple is a device for measuring temperature consisting of a pair of wires of different metals or semiconductors joined at both ends. One junction is at the temperature to be measured, the second at a fixed temperature. The electromotive force generated depends upon the temperature difference

CONCEPT:

• The thermodynamical system is a body of matter or radiation which is confined in space by walls, which separates it from the surroundings.  

• The system is separated from the surrounding by the boundary. 
• The different types of thermodynamic walls are
• Diathermic wall:  This is the type of wall that allows the flow of heat between the system and surroundings. 
  • A hot cup of Tea is an example of a Diathermic wall.
• Adiabatic wall: This type of wall that doesn't allow the flow of heat between the system and surroundings.​
• There are 3 types of a thermodynamical system     

1. Open System: The type of system that can exchange heat and temperature with surroundings.
2. Closed System: The type of system in which the exchange of energy is only possible but not matter.
3. Isolated System: The type of system which cannot exchange either matter or energy with its surrounding.

SOLUTION:

• From above it is clear that, adiabatic walls are the walls that separate a thermodynamical system and boundary and don't allow the passage of heat or matter between the thermodynamical systems.

Concept:

Temperature: 

• It is the measure of the degree of hotness and coldness of a body.
• The SI unit of temperature is Kelvin (K).

The major temperature scales are:

• Celsius scale: It is also known as the centigrade scale, and most commonly used scale. It is defined from assigning 0°C to 100°C of freezing and boiling point of water at 1 atmospheric pressure.
• Kelvin scale: It is the base unit of temperature, denoted with K.
  • There are no negative numbers on the Kelvin scale as the lowest is 0 K.

The relation between Celsius and Kelvin is given by:

°C + 273.15 = K

Explanation:

Absolute zeroTemperature:

• Absolute zero temperature is the lower limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach its minimum value, taken as 0.
• It is 0 K i.e. −273.15° C or −459.67° F.
• It is impossible to reach zero temperature.
• In practice, work can never achieve absolute zero temperature because as it is impossible to have a source to supply an infinite amount of work.

The correct answer is 298K.

• The basic formula is °C + 273.15 = K.
  So, reading on a Kelvin scale is 25^∘C + 273 = 298K. So, option 1 is correct.

• 0°C is equal to 273.15 Kelvins.
• To convert Fahrenheit degrees into Kelvins, (°F − 32) × 5/9 + 273.15 = K.
• Absolute zero is 0 Kelvins. This is the lowest temperature of any substance.
• Water freezes at 0 degrees Celsius or 32 Degrees Fahrenheit, or 273.15 Kelvins.
• Water boils at 100 degrees Celsius or 212 degrees Fahrenheit, or 373.15 Kelvins.

Important Points

• The formula conversion between Fahrenheit and Celsius is: C/5 = (F-32)/9
• The Celsius scale and the Fahrenheit scale coincide at -40°, which is the same for both.

The correct answer is -40°.

Key Points

• The Celsius scale and the Fahrenheit scale coincides at -40°, which is the same for both.
• The formula conversion between Fahrenheit and Celsius is: C/5 = (F-32)/9

Additional Information

• Water boils at 100 degrees Celsius or 212 degrees Fahrenheit, or 373.15 Kelvins.
• Water freezes at 0 degrees Celsius or 32 Degrees Fahrenheit, or 273.15 Kelvins.
• Absolute zero is 0 Kelvins, this is the lowest temperature of any substance.
• 0°C is equal to 273.15 Kelvins, The basic formula is °C + 273.15 = K.
• To convert Fahrenheit degrees into Kelvins, (°F − 32) × 5/9 + 273.15 = K.