Temperature — Set 3
Physics · तापमान · Questions 21–30 of 50
How many fixed points are commonly used to calibrate a simple laboratory thermometer scale?
Correct Answer: B. Two fixed points
A basic thermometer scale is commonly set using two fixed points. These are often the ice point and steam point of water under standard conditions. Two points define a linear scale between them.
A bimetallic strip thermometer works mainly due to which principle?
Correct Answer: A. Different metals expand by different amounts when heated
A bimetallic strip bends because its two metals have different thermal expansion rates. Heating causes one side to expand more than the other. This bending is used in thermostats and temperature switches.
Absolute zero on the Celsius scale is approximately equal to which value?
Correct Answer: B. -100°C
Absolute zero is the lowest limit of temperature on the thermodynamic scale. On the Celsius scale it is about -273.15°C. At this limit, idealized thermal motion approaches a minimum.
Which temperature corresponds to the same numerical reading on both Celsius and Fahrenheit scales?
Correct Answer: C. -40°
Celsius and Fahrenheit match at one special temperature. Using the conversion relation shows the equality occurs at -40. So -40 is the same number on both scales.
Which statement about the size of a temperature interval is correct?
Correct Answer: B. A change of 1 K equals a change of 1°C
The correct answer is 'A change of 1 K equals a change of 1°C'. The kelvin and Celsius scales have equal-sized steps. A difference of 1 K corresponds to a difference of 1°C. Their zero points differ, but the interval size is the same.
98.6°F is approximately equal to how many degrees Celsius?
Correct Answer: D. 37°C
Use C = (F - 32) × 5/9 to convert Fahrenheit to Celsius. For 98.6°F, (98.6 - 32) × 5/9 equals about 37°C. This value is close to normal human body temperature.
Which instrument is often used as a standard for accurate temperature measurement because it relates closely to thermodynamic temperature?
Correct Answer: D. Constant volume gas thermometer
A gas thermometer relates temperature to gas pressure or volume in a predictable way. It can approximate the thermodynamic temperature scale well. This makes it useful as a reference for calibration.
Which statement about the kelvin scale is correct?
Correct Answer: D. Its zero corresponds to absolute zero
The kelvin scale starts from absolute zero. Absolute zero is the theoretical lowest temperature limit. This is why kelvin is called an absolute temperature scale.
Which relation correctly converts Celsius temperature t to kelvin temperature T?
Correct Answer: C. T = t + 273.15
Kelvin temperature is obtained by adding 273.15 to the Celsius value. This shifts the zero point from 0°C to absolute zero. The size of one step remains the same in both scales.
Why is the boiling point of water not always exactly 100°C in everyday conditions?
Correct Answer: B. Because boiling point depends on external pressure
The boiling point of water changes with atmospheric pressure. Lower pressure makes water boil at a lower temperature and higher pressure raises it. The value 100°C is for standard pressure conditions.