A stationary wave is set up in a resonance air column of a glass tube partially filled with water by holding a tuning fork near the open end, the open end of the tube is :

Options

A. Always a node
B. Always an antinode
C. Sometimes a node and sometimes an antinode
D. Neither a node nor an antinode

Answer

To solve the question regarding the nature of the open end of a glass tube partially filled with water when a stationary wave is set up, we can follow these steps:

### Step 1: Understand the Setup
We have a glass tube that is partially filled with water. The air column above the water will vibrate when a tuning fork is held near the open end of the tube.

**Hint:** Visualize the tube and the position of the water level to understand the air column's behavior.

### Step 2: Identify the Type of Tube
Since the tube is closed at one end (the water surface) and open at the other end, it behaves like a closed-end pipe.

**Hint:** Remember that the closed end of a tube is where the displacement node occurs.

### Step 3: Apply the Boundary Conditions
In a closed-end pipe:
- The closed end (where the water is) will have a displacement node (minimum displacement).
- The open end will have a displacement anti-node (maximum displacement).

**Hint:** Recall that at an open end, the air can move freely, leading to maximum displacement.

### Step 4: Conclude the Nature of the Open End
Since the open end of the tube is where the maximum displacement occurs, we can conclude that it is always an anti-node.

**Hint:** Think about how sound waves behave at open and closed ends to reinforce your understanding.

### Final Answer
The open end of the tube is always an anti-node.