Thermocouple made up of:
Understanding Thermocouple Composition
A thermocouple is a sensor used to measure temperature. It consists of two different types of metals joined together at one end. When this junction is heated or cooled, a voltage is produced that can be correlated to the temperature. This phenomenon is known as the Seebeck effect.
Common Thermocouple Types
Thermocouples are available in different types, identified by letters (e.g., Type K, Type J, Type T). Each type uses a specific combination of metals, which determines its temperature range, accuracy, and suitability for different environments.
Composition of Common Thermocouples
Let's look at the composition of some common thermocouple types:
- Type K: Nickel-Chromium (Positive leg, often called Chromel) and Nickel-Aluminum (Negative leg, often called Alumel).
- Type J: Iron (Positive leg) and Constantan (Copper-Nickel alloy) (Negative leg).
- Type T: Copper (Positive leg) and Constantan (Copper-Nickel alloy) (Negative leg).
- Type E: Nickel-Chromium (Chromel) (Positive leg) and Constantan (Copper-Nickel alloy) (Negative leg).
There are also other types like R, S, and B which use precious metals like Platinum and Rhodium for high-temperature applications.
Analyzing the Given Options for Thermocouple Materials
The question asks about the material composition of a thermocouple from the given options. Let's examine each option:
- Tungsten - Copper: While Tungsten is used in some high-temperature thermocouples (like Type C, composed of Tungsten-5% Rhenium and Tungsten-26% Rhenium), Copper is typically used with Constantan (Type T) and not commonly paired directly with Tungsten in standard thermocouples.
- Ferrous - aluminum: Ferrous materials (Iron-based) are used in thermocouples (like Type J which uses Iron), but pairing Ferrum (Iron) directly with Aluminum is not a standard combination for common thermocouples.
- Nickel - Chromium: Nickel-Chromium is the material used for the positive leg (Chromel) in the very common Type K thermocouple. The negative leg is Nickel-Aluminum (Alumel). The combination Nickel-Chromium is directly associated with a widely used thermocouple type.
- Ferrous - Chromium: Ferrous materials (Iron) are used in Type J, and Chromium is a component in the Nickel-Chromium alloy (Chromel) of Type K, but a direct pairing of Ferrous (Iron) and Chromium is not standard for common thermocouples.
Based on the standard compositions of common thermocouples, the pairing Nickel - Chromium is the most appropriate choice from the given options, representing the positive leg material of the popular Type K thermocouple.
Conclusion
A common thermocouple, specifically Type K, is made using Nickel-Chromium and Nickel-Aluminum alloys. From the provided choices, Nickel - Chromium accurately identifies a key component pair (the positive leg) of a standard thermocouple construction.
| Thermocouple Type | Positive Leg | Negative Leg |
|---|---|---|
| Type K | Nickel-Chromium (Chromel) | Nickel-Aluminum (Alumel) |
| Type J | Iron | Constantan (Copper-Nickel) |
| Type T | Copper | Constantan (Copper-Nickel) |
Revision Table: Key Thermocouple Facts
| Concept | Description |
|---|---|
| What is a Thermocouple? | Temperature sensor made of two different metals joined. |
| Working Principle | Seebeck Effect (voltage generated due to temperature difference). |
| Common Materials (Type K) | Nickel-Chromium and Nickel-Aluminum. |
| Purpose | Measuring temperature over a wide range. |
Additional Information on Thermocouples
Thermocouples are robust and versatile temperature sensors. Their range of application varies greatly depending on the type of metal used. For instance, Type K thermocouples are widely used in industrial and scientific applications due to their wide temperature range (-200°C to +1250°C) and relatively low cost. The voltage generated is typically in the millivolt (<span style="white-space: nowrap;">mV</span>) range and requires a measurement device that can accurately read these small voltages.
The Seebeck effect is a thermoelectric phenomenon where a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances. This effect is reversible, and its inverse is the Peltier effect.
Important Questions from Miscellaneous
A stone is thrown horizontally from the top of a 20 m high building with a speed of 12 m/s. It hits the ground at a distance R from the building. Taking g = 10 m/s2 and neglecting air resistance will give :
A sphere of volume V is made of a material with lower density than water. While on Earth, it floats on water with its volume f1V (f1 < 1) submerged. On the other hand, on a spaceship accelerating with acceleration a < g (g is the acceleration due to gravity on Earth) in outer space, its submerged volume in water is f2V. Then:
A railway wagon (open at the top) of mass M1 is moving with speed v1 along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes M2 and speed becomes v2. Taking the rain to be falling vertically and the water stationery inside the wagon, the relation between the two speeds v1 and v2 is :
Consider the following statements:
1. Distance between the longitudes becomes zero on North Pole and South Pole.
2. Distance between the longitudes is maximum on the Equator.
3. Number of longitudes is more than number of latitudes.
Which of the statements given above is/are correct?
One block of 2⋅0 kg mass is placed on top of another block of 3⋅0 kg mass. The coefficient of static friction between the two blocks is 0⋅2. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as 10 m/s2, the maximum value of the frictional force is :
