In a resonace tube experiment, the first resonance is obtained when the level of the water in the tube is at 20 cm from the open end. Resonace will also be obtained when the distance of the water level from the open end is

Options

A. 40 cm from the open end
B. 60 cm from the open end
C. 80 cm from the open end
D. 100 cm from the open end

Explanation

To solve the problem regarding the resonance tube experiment, we need to understand the relationship between the length of the air column in the tube and the wavelengths of the sound waves involved.

### Step-by-Step Solution:

1. **Identify the First Resonance Condition**:
The first resonance occurs when the length of the air column (L) is equal to \( \frac{\lambda}{4} \), where \( \lambda \) is the wavelength of the sound wave. Given that the first resonance is at 20 cm, we can write:
\[
L_1 = \frac{\lambda}{4} = 20 \text{ cm}
...