A radar sends an electromagnetic single of electric (E₀) = 2.25 V/m and magnetic field (B₀) = 1.5 × 10^-⁸ T which strikes a target on line of sight at a distance of 3km in a medium. After that, a part of signal (echo) reflects back towards the radar with same velocity and by same path. If the signal was transmitted at time t = 0 from radar, then after how much time echo will reach to the radar?

Option 1 -

2.0 * 10^-5s

Option 2 -

4.0 * 10^-5 s

Option 3 -

1.0 * 10^-5 s

Option 4 -

8.0 * 10^-⁵ s

3 Views | Posted 3 weeks ago

Asked by Shiksha User

1 Answer

Answered by

Raj Pandey | Contributor-Level 9

3 weeks ago

Correct Option - 2

Detailed Solution:

$E_{0} = 2.25 \frac{v}{m}$ Speed of declromagnetic signal, $v = \frac{E_{0}}{B_{0}} = \frac{2.25 v / m}{1.5 \times 1 0^{- 8} T}$

$B_{0} = 1.5 \times 1 0^{- 8} T \Rightarrow v = \frac{225}{150} \times 1 0^{8} = 1.5 \times 1 0^{8} m / s$

Time to reach each to the same

radar, $t = \frac{2 \times 3 \times 1 0^{3} m}{1.5 \times 1 0^{8} m / s} = 4 \times 1 0^{- 5} S$

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