Category: Class 11 Physics Objective Questions

Physics Multiple Choice Questions on “Measurement of Temperature”.

1. Temperature is absolute. True or False?
a) True
b) False
Answer: b
Clarification: Temperature is a relative measure. When we touch a body we say it is hold or cold. We use devices like thermometers to indicate temperatures but we don’t have any fixed absolute value. When we say that temperature is 25°, it is relative to a reference we have decided like steam point and ice point.

2. What is the slope of line drawn for a graph between temperature in °C & °F?
a) 1.8
b) 5/9
c) slope is variable
d) 2
Answer: a
Clarification: °F = (9/5)°C + 32.
Therefore from this we can say that slope of line drawn for graph between temperature in °C & °F is 9/5 = 1.8.

3. Why is mercury used in thermometers?
a) It volume is proportional to square of increase of temperature
b) It shows linear variation in volume with temperature
c) Its volume remains constant with temperature
d) Its volume decreases with increase in temperature
Answer: b
Clarification: For measuring temperature in a thermometer we need a substance whose physical properties change with temperature and can be easily related with temperature. Mercury’s volume increases linearly with increase in temperature and hence we can create a scale on the thermometer accordingly.

4. Temperature is 300K. Convert it into ℉.
a) 47°F
b) 80.6°F
c) 27°F
d) 16.6°F
Answer: b
Clarification: Temperature in K = 273 + temp in °C.
∴ Temp in °C = 300-273 = 27
°F = (9/5) °C + 32
= (9/5)*27 + 32
= 80.6°F.

Physics Multiple Choice Questions on “Second Law of Thermodynamics”.

1. A process is carried out between 2 systems. It is possible for entropy of one system to decrease. True or False?
a) True
b) False
Answer: a
Clarification: The net entropy change has to be positive. It is possible for the entropy of a system to decrease, but the entropy of the second system should increase enough to ensure net entropy increases.

2. According to the first law of thermodynamics, a book lying on a table can fly upwards on its own by using the internal energy of the table. True or False?
a) True
b) False
Answer: a
Clarification: In the above said process, energy is conserved and according to first law, this is valid. It only violates the second law. So, the given statement is true.

3. Which law of thermodynamics says that efficiency of a heat engine cannot be 1?
a) First
b) Zeroth
c) Second
d) Third
Answer: c
Clarification: The second law of thermodynamics fundamentally disallows many processes that may be consistent with the law of conservation of energy. It says that entropy change in an irreversible process has to be positive. This means that heat given to an engine can’t all be converted into work. Therefore, efficiency cannot be 1.

4. Which of the following is the Kelvin Planck statement?
a) Heat from a cold reservoir cannot be transferred to a hot reservoir without external work
b) Efficiency for a reversible cyclic process can be 1
c) Heat from a hot reservoir can be completely converted into work if process is reversible
d) Efficiency of a heat engine is less than 1
Answer: d
Clarification: Kelvin Planck statement is: No process is possible whose sole result is the absorption of heat from a reservoir and complete conversion of that heat into work. So, this implies that efficiency of a heat engine is less than 1.

5. The second law of thermodynamics states that?
a) Entropy of an isolated system can never decrease over time
b) Entropy of a pure crystalline substance at 0K is 0
c) Energy is conserved
d) Entropy of a system can never decrease
Answer: a
Clarification: The second law states that entropy of an isolated system can never decrease over time. There can be a system whose entropy decreases, but, at the same time in that process another system’s increase in entropy will more than compensate for that decrease.

Physics Multiple Choice Questions on “Transverse and Longitudinal Waves”.

1. All waves require material for propagation. True or False?
a) True
b) False
Answer: b
Clarification: Only material waves,like the name suggests, require material for propagation. Electromagnetic waves on the other hand don’t require any medium. They can travel through vacuum in the form of electric and magnetic fields.

2. Transverse waves involve energy transfer by movement of medium particles, while longitudinal waves don’t. True or False?
a) True
b) False
Answer: b
Clarification: Transverse waves involve vibration, & not movement, of medium particles to transfer energy. Even in longitudinal waves, medium particles move up & down but don’t travel to transfer energy.

3. Electromagnetic waves are considered to be which of the following types?
a) Transverse
b) Longitudinal
c) Both Transverse & Longitudinal
d) Neither longitudinal nor transverse
Answer: a
Clarification: Electromagnetic waves are formed by transverse motion of electric & magnetic fields. Thus, they are said to be transverse waves.