The speed of a waves is 350 m/s and wavelength is 70 cm. The frequency of wave is :

Options

A. 500 Hz
B. 700 Hz
C. 50 Hz
D. 200 Hz

Explanation

To find the frequency of a wave given its speed and wavelength, we can use the formula:

\[ v = n \cdot \lambda \]

Where:
- \( v \) is the speed of the wave,
- \( n \) is the frequency of the wave,
- \( \lambda \) is the wavelength.

### Step-by-Step Solution:

1. **Identify the given values:**
- Speed of the wave, \( v = 350 \, \text{m/s} \)
- Wavelength, \( \lambda = 70 \, \text{cm} \)

2. **Convert the wavelength from centimeters to meters:**
- Since \( 1 \, \text{cm} = 0.01 \, \text{m} \),
- Therefore, \( \lambda = 70 \, \text{cm} = 70 \times 0.01 \, \text{m} = 0.70 \, \text{m} \).

3. **Rearrange the formula to solve for frequency \( n \):**
- From the formula \( v = n \cdot \lambda \), we can rearrange it to find \( n \):
\[ n = \frac{v}{\lambda} \]

4. **Substitute the known values into the equation:**
- Now we can substitute \( v = 350 \, \text{m/s} \) and \( \lambda = 0.70 \, \text{m} \):
\[ n = \frac{350 \, \text{m/s}}{0.70 \, \text{m}} \]

5. **Calculate the frequency:**
- Performing the division:
\[ n = \frac{350}{0.70} = 500 \, \text{Hz} \]

### Conclusion:
The frequency of the wave is \( 500 \, \text{Hz} \).