Physics

Thermal Properties and Thermodynamics

380 Questions

Thermal properties and thermodynamics questions evaluate concepts of heat transfer, thermal efficiency, and temperature variations. Problems involve calculating heat content, conductivity, and the performance of heat engines. This subject is regularly tested in physics sections across multiple competitive platforms.

Heat transfer calculationsThermal efficiencyBlack body radiationTemperature variationsRefrigeration performance

Thermal Properties and Thermodynamics Questions

Multiple choice general knowledge science & technology

Stefan boltzmann law is

  1. The radiated power of a hot body is proportional to the radiating surface area and the fourth power of the thermodynamic temperature

  2. The radiated power of a hot body is proportional to the radiating surface area and the cube of the thermodynamic temperature

  3. The radiated power of a hot body is proportional to the radiating surface area and the square of the thermodynamic temperature

  4. The radiated power of a hot body is proportional to the radiating surface area and the thermodynamic temperature
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stefan-Boltzmann Law (1879-1884) states that total radiated power P = σAT⁴, where σ is Stefan-Boltzmann constant (5.67×10⁻⁸ W·m⁻²·K⁻⁴), A is surface area, T is absolute temperature in Kelvin. The T⁴ dependence is key.

Multiple choice general knowledge science & technology

Specific heat ratio

  1. ? = Cv / Cp

  2. ? = Cp / Cv

  3. ? = Cp Cv

  4. ? = m / Cp Cv
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The specific heat ratio (γ or kappa) is the ratio of specific heat at constant pressure (Cp) to specific heat at constant volume (Cv). It's a crucial parameter in thermodynamics and fluid mechanics.

Multiple choice general knowledge science & technology

The value of thermal voltage (VT)at 300K is

  1. .26 mV

  2. 2.6 mV

  3. 26 mV

  4. It depends upon the applied potential
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To solve this question, the user needs to know the definition of thermal voltage and its value at room temperature.

Thermal voltage (VT) is the voltage equivalent of the thermal energy of a particle. It is given by the formula:

VT = kT/q

where k is the Boltzmann constant, T is the temperature in Kelvin, and q is the charge of a particle.

At room temperature (300K), the value of VT can be calculated as:

VT = (kT/q) = (1.38 x 10^-23 J/K x 300K) / 1.6 x 10^-19 C

Simplifying this expression, we get:

VT = 0.0259 V = 25.9 mV

Therefore, the answer is:

The Answer is: C. 26 mV

Multiple choice

Two bodies A and B are of same mass, and same amount of heat is given to both of them. If the temperature of A increases more than that of B because of heat addition, then-

  1. The specific heat capacity of A is more than that of B.

  2. The specific heat capacity of A is less than that of B.

  3. Both A and B have the same specific heat capacity but A has grater thermal conductivity.

  4. Both A and B have the same specific heat capacity but B has grater thermal conductivity.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Specific heat capacity is the amount of heat required to raise the temperature of a substance by 1 degree. If A heats up more than B with the same heat, A must have lower specific heat capacity (Q = mcΔT).

Multiple choice

Arrhenius equation is

  1. K = Ae-1/RT

  2. K = e-RT/Ea

  3. K = A e-Ea/RT

  4. K = A eEa/RT
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Arrhenius equation K = A e^(-Ea/RT) correctly relates the rate constant K to temperature T, where A is the pre-exponential factor, Ea is activation energy, and R is the gas constant. Option A has incorrect exponent form, B lacks the pre-exponential factor, and D has positive exponent instead of negative.