The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT . The peak value of electric field strength is :

Options

A. 6 V/m
B. 9V/m
C. 12 V/m
D. 3 V/m

Explanation

To find the peak value of the electric field strength (E₀) in a traveling electromagnetic wave given the peak value of the magnetic field (B₀), we can use the relationship between the electric field and magnetic field in electromagnetic waves.

### Step-by-Step Solution:

1. **Identify the given values:**
- The peak value of the magnetic field (B₀) is given as 20 nT (nano tesla).
- Convert this value into teslas:
\[ B₀ = 20 \, \text{nT} = 20 \times 10^{-9} \, \text{T} \]

2. **Use the relationship between electric field and magnetic field:**
- The relationship is given by:
\[ E₀ = c \cdot B₀ \]
- Where \( c \) is the speed of light in vacuum, approximately \( 3 \times 10^8 \, \text{m/s} \).

3. **Substitute the values into the equation:**
- Now substitute \( B₀ \) and \( c \) into the equation:
\[ E₀ = (3 \times 10^8 \, \text{m/s}) \cdot (20 \times 10^{-9} \, \text{T}) \]

4. **Calculate the electric field strength:**
- Perform the multiplication:
\[ E₀ = 3 \times 20 \times 10^{8 - 9} = 60 \times 10^{-1} \, \text{V/m} \]
- Simplifying gives:
\[ E₀ = 6 \, \text{V/m} \]

5. **Final answer:**
- The peak value of the electric field strength is:
\[ E₀ = 6 \, \text{V/m} \]