Problem 6 - Arihant AIEEE Physics

Question

Mark correct option or options: (a) Sun temperature is measured by radiation pyrometer (b) Insect temperature is measured by thermocouple thermometer (c) Moon's temperature is measured by berthometer (d) All of the above

Step-by-Step Solution

Answer

Correct options are (a) and (b).

Step 1: Understand the Instruments

We first need to understand what each instrument mentioned does. A radiation pyrometer measures temperature based on radiation emitted. A thermocouple thermometer measures temperature through the direct contact of its sensors with a surface, generating a voltage that can be correlated with temperature. A berthometer is not a recognized instrument in thermometry, therefore we consider it fictional, or incorrect in this context.

Step 2: Evaluate Statement (a)

The sun's temperature can indeed be measured using a radiation pyrometer, as the sun emits radiation that can be detected from a distance. Therefore, statement (a) is correct.

Step 3: Evaluate Statement (b)

Insect temperature can be measured using a thermocouple thermometer if the sensor can make adequate contact with the insect’s surface to get an accurate reading. So, statement (b) is correct.

Step 4: Evaluate Statement (c)

The moon's temperature is actually measured using instruments such as infrared telescopes and not a berthometer, as no such instrument exists. Thus, statement (c) is incorrect.

Step 5: Determine Correct Options

Based on the analysis, statements (a) and (b) are correct. Therefore, 'All of the above' cannot be the correct answer as statement (c) is incorrect.

Key Concepts

Radiation Pyrometer

Radiation pyrometers are fascinating devices used to measure temperature from a distance. They work by detecting the thermal radiation emitted by an object. This method is particularly useful for measuring very high temperatures, where direct contact with a thermometer would be impractical or impossible.

Radiation pyrometers are commonly used in industrial settings, such as in furnaces or kilns, and even to measure the temperature of astronomical objects like the sun. The principle of operation is straightforward:

• The device focuses radiation from the object through an optical system.
• This radiation is then converted into an electric signal.
• Finally, the electric signal is translated into a temperature reading, often displayed digitally.

The advantage of pyrometers over contact thermometers is their ability to measure temperature without making physical contact with the object being measured. This makes them ideal for measuring objects at extreme temperatures or those that are difficult to access.

Thermocouple Thermometer

A thermocouple thermometer is a type of contact thermometer that measures temperature through the thermoelectric effect. This effect takes advantage of the junction of two different metals, which generates a voltage when exposed to temperature changes.

Thermocouples are widely used because they are:

• Durable and suitable for a wide range of environments.
• Able to measure a vast range of temperatures, from extremely cold to extremely hot.
• Relatively inexpensive compared to other high-accuracy temperature measurement tools.

The operation is as follows:

• Two wires made from different metals are joined at one end to form a junction.
• When the junction experiences a temperature change, it produces a voltage correlating with that change.
• This voltage is measured and converted into a readable temperature.

Thermocouples are widely used in various applications, from measuring the surface temperature of small creatures, like insects, to monitoring temperature in industrial processes.

Infrared Telescopes

Infrared telescopes are powerful tools used by astronomers to detect and measure temperatures of celestial objects. Unlike visible light telescopes, infrared telescopes focus on the invisible infrared spectrum, which is essentially heat and radiation emitted by objects.

Their ability to detect infrared radiation is invaluable when observing phenomena such as:

• Stars and planets that are cool and emit most of their energy in the infrared spectrum.
• Dust clouds in space, which absorb visible light but emit infrared radiation.
• Galaxies that are distant, allowing astronomers to peer into the past.

The technique used by infrared telescopes involves:

• Collecting infrared radiation with large mirrors or lenses.
• Focusing this radiation onto sensitive detectors.
• Converting these detections into images or data that can be analyzed.

This technology has enabled remarkable discoveries about the universe, giving us insights into places not visible to the naked eye.