Temperature in physics class 11
In Physics, Temperature is defined as a measure of the average kinetic energy of the particles (atoms or molecules) in a substance. It is a scalar quantity that indicates how hot or cold an object is.
Key Points about Temperature:
1. Kinetic Energy of Particles: As the particles of a substance move, they possess kinetic energy. The faster the particles move, the higher the temperature of the substance.
2. Thermal Equilibrium: When two objects are in thermal contact, heat will flow from the hotter object to the cooler one until both objects reach the same temperature, which is known as thermal equilibrium.
3. Units of Temperature:
- Celsius (°C): A commonly used unit for temperature, where 0°C is the freezing point of water and 100°C is the boiling point.
- Kelvin (K): The SI (International System of Units) unit for temperature. The Kelvin scale starts at absolute zero (0 K), where particles have minimum thermal energy.
4. Temperature Scales:
- Celsius Scale: Based on the freezing and boiling points of water.
- Fahrenheit Scale: Used primarily in the U.S., with freezing at 32°F and boiling at 212°F.
- Kelvin Scale: The absolute scale, starting from 0 K (absolute zero), which is the lowest possible temperature.
Concept of Heat and Temperature:
- Heat is the energy transferred between systems or objects due to a temperature difference. It flows from the higher temperature body to the lower temperature one.
- Temperature itself is not energy; rather, it is a measure of how much energy the particles in a substance possess on average.
Question 1: What is the unit of temperature in the SI system?
A) Celsius
B) Fahrenheit
C) Kelvin
D) Joule
Answer: C) Kelvin
Question 2: Temperature is a measure of:
A) Total energy of particles
B) Average kinetic energy of particles
C) Average potential energy of particles
D) Heat energy of the system
Answer: B) Average kinetic energy of particles
Question 3: Which of the following is the lowest possible temperature?
A) 0°C
B) 0°F
C) 0 K
D) -273°C
Answer: C) 0 K
Question 4: The temperature at which the Celsius and Fahrenheit scales are equal is:
A) -40°C
B) -273°C
C) 0°C
D) 100°C
Answer: A) -40°C
Question 5: The boiling point of water on the Kelvin scale is:
A) 100 K
B) 273 K
C) 373 K
D) 273°C
Answer: C) 373 K
Question 6: The freezing point of water on the Kelvin scale is:
A) 0 K
B) 273 K
C) 100 K
D) 273°C
Answer: B) 273 K
Question 7: What is the main principle behind the functioning of a thermometer?
A) Thermal conductivity
B) Expansion of liquids with temperature
C) Gravitational force
D) Electric current
Answer: B) Expansion of liquids with temperature
Question 8: What is the temperature at which all molecular motion ceases?
A) 0°C
B) 0 K
C) -273°C
D) 100°C
Answer: B) 0 K
Question 9: What is the fundamental difference between heat and temperature?
A) Heat is a measure of the total energy; temperature is the measure of average energy
B) Heat is the motion of particles; temperature is the transfer of energy
C) Heat is the energy of a system; temperature is the energy of the surroundings
D) There is no difference between heat and
temperature
Answer: A) Heat is a measure of the total energy; temperature is the measure of average energy
Question 10: Which of the following is true about the Kelvin scale?
A) It has negative values
B) It is based on the freezing point of water
C) It starts from absolute zero
D) It uses the same intervals as the Celsius scale
Answer: C) It starts from absolute zero
Question 11: What is the main factor that determines the temperature of an object?
A) Its size
B) Its material composition
C) The average kinetic energy of its particles
D) Its colour
Answer: C) The average kinetic energy of its particles
Question 12: The Celsius and Kelvin scales have the same:
A) Zero point
B) Interval size
C) Number of divisions
D) Both A and B
Answer: B) Interval size
Question 13: If an object has a temperature of 0°C, its temperature in Kelvin is:
A) 273 K
B) 273°C
C) 0 K
D) 100 K
Answer: A) 273 K
Question 14: The Kelvin scale is based on:
A) Boiling and freezing points of water
B) Absolute zero
C) The density of water
D) The expansion of liquids
Answer: B) Absolute zero
Question 15: A thermometer measures temperature using the property of:
A) Conductivity
B) Expansion
C) Compression
D) Diffusion
Answer: B) Expansion
Question 16: What is the freezing point of water in Fahrenheit?
A) 0°F
B) 32°F
C) 100°F
D) 212°F
Answer: B) 32°F
Question 17: The difference in temperature between 1°C and 1 K is:
A) 1/2
B) 1
C) 2
D) 10
Answer: B) 1
Question 18: In which of the following scales does water freeze at 0 and boil at 100?
A) Celsius
B) Kelvin
C) Fahrenheit
D) Rankine
Answer: A) Celsius
Question 19: What is the temperature of absolute zero in Celsius?
A) 0°C
B) -273°C
C) -100°C
D) 100°C
Answer: B) -273°C
Question 20: Which of the following laws defines temperature in terms of thermal equilibrium?
A) Zeroth Law of Thermodynamics
B) First Law of Thermodynamics
C) Second Law of Thermodynamics
D) Third Law of Thermodynamics
Answer: A) Zeroth Law of Thermodynamics
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