An electric fan is switched on in a closed room. The air in the room is

Options

A. Cooled
B. Heated
C. Maintains its temperature
D. Heat or cooled depending on the atmospheric pressure

Explanation

To solve the question "An electric fan is switched on in a closed room. The air in the room is:", we can analyze the situation step by step.

### Step-by-Step Solution:

1. **Understanding the Environment**: When the fan is switched on in a closed room, it creates airflow. The air in the room is initially at a certain temperature.

**Hint**: Consider the initial state of the air before the fan is turned on.

2. **Energy Conversion**: The fan operates by converting electrical energy into mechanical energy. This mechanical energy is used to rotate the blades of the fan, which moves the air around.

**Hint**: Think about how energy transformations occur in electrical devices.

3. **Effect on Air Molecules**: As the fan blades rotate, they disturb the air molecules. This disturbance causes the air molecules to move more rapidly, increasing their kinetic energy.

**Hint**: Recall the relationship between kinetic energy and temperature in gases.

4. **Increase in Collisions**: With the increased speed of the air molecules, the frequency of collisions between the air molecules also increases. More collisions mean that the energy is being transferred between the molecules more frequently.

**Hint**: Consider how molecular motion and collisions relate to temperature and heat.

5. **Heat Generation**: The increased kinetic energy from the collisions among the air molecules leads to an increase in the thermal energy of the air. This results in a rise in temperature within the room.

**Hint**: Reflect on how heat is generated in a system where energy is being converted and transferred.

6. **Conclusion**: Therefore, when the fan is switched on, the air in the room becomes heated due to the increased kinetic energy and collisions of air molecules.

**Hint**: Summarize the overall effect of the fan on the air temperature in the room.

### Final Answer:
The air in the room is heated when the electric fan is switched on.