The process of transmission of heat in which no medium is required is/are known as

Options

A. Conduction
B. Convection
C. Radiation
D. All of these

Explanation

To solve the question, "The process of transmission of heat in which no medium is required is/are known as," we will analyze the three processes of heat transfer: conduction, convection, and radiation.

### Step-by-Step Solution:

1. **Understanding Heat Transfer Processes**:
- Heat can be transferred in three main ways: conduction, convection, and radiation.

2. **Defining Conduction**:
- Conduction is the process where heat is transferred through direct contact between materials. For example, when a metal spoon is placed in a hot soup, heat travels from the soup to the spoon. This process requires a medium (the spoon and the soup).

3. **Defining Convection**:
- Convection is the transfer of heat in fluids (liquids and gases) through the movement of the fluid itself. For example, when water is heated in a pot, the hot water rises and the cooler water moves down to take its place. This process also requires a medium (the fluid).

4. **Defining Radiation**:
- Radiation is the transfer of heat in the form of electromagnetic waves. It does not require a medium to travel. For example, the heat from the sun reaches the Earth through the vacuum of space. This is the only process among the three that can occur without a medium.

5. **Conclusion**:
- Since conduction and convection require a medium for heat transfer, and radiation does not, the answer to the question is **radiation**.

### Final Answer:
The process of transmission of heat in which no medium is required is known as **radiation**.

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