The study of physical phenomenon at temperature below liquid nitrogen is called

Options

A. refrigeration
B. conduction
C. cryogenics
D. radiation

Answer

To solve the question, we need to identify the correct term that describes the study of physical phenomena at temperatures below the boiling point of liquid nitrogen.

### Step-by-Step Solution:

1. **Identify the Boiling Point of Nitrogen**:
- The boiling point of nitrogen is approximately -195.79 degrees Celsius. This is the temperature at which nitrogen transitions from a gas to a liquid.

2. **Understand the Context of the Question**:
- The question is asking for a specific term that refers to the study of physical phenomena occurring at temperatures below this boiling point.

3. **Evaluate the Options**:
- Option 1: Refrigeration - This refers to the process of cooling substances, not specifically the study of phenomena at low temperatures.
- Option 2: Conduction - This is a method of heat transfer, not related to low-temperature phenomena.
- Option 3: Cryogenics - This term specifically refers to the study of materials and phenomena at very low temperatures, particularly below the boiling point of liquid nitrogen.
- Option 4: Radiation - This refers to the emission of energy as electromagnetic waves, not specifically related to low temperatures.

4. **Select the Correct Answer**:
- Based on the evaluation, the correct answer is **Cryogenics**, as it directly pertains to the study of physical phenomena at temperatures below the boiling point of liquid nitrogen.

### Final Answer:
The study of physical phenomena at temperatures below liquid nitrogen is called **Cryogenics**.