A radar sends an electromagnetic signal of electric field (E0) = 2.25… | JEE Main 2022 (28 Jun, Shift 1)

Q14JEE Main 2022 · 28 JUN · SHIFT 1Medium

Speed of EM Waves in a Medium

A radar sends an electromagnetic signal of electric field (E0) = 2.25 V/m and magnetic field (B0) = 1.5 $\times$ 10 $-$ 8 T which strikes a target on line of sight at a distance of 3 km 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?

Show answer and solution

Answer: (b)

Speed in the medium $v = \dfrac{E_0}{B_0} = \dfrac{2.25}{1.5 \times 10^{-8}} = 1.5 \times 10^{8}$ m/s
Echo travels to the target and back: distance $= 2 \times 3000 = 6000$ m.
$t = \dfrac{6000}{1.5 \times 10^{8}} = 4.0 \times 10^{-5}$ s
So the answer is (b) $4.0 \times 10^{-5}$ s.

Report a mistake

More questions on Speed of EM Waves in a Medium

A plane electromagnetic wave travels in a medium of relative permeability 1.61 and…JEE Main 2022 (24 Jun, Shift 1)
Electric field in a plane electromagnetic wave is given by E = 50 sin(500x - 10 × 1010 t)…JEE Main 2021 (27 Aug, Shift 1)
The relative permittivity of distilled water is 81. The velocity of light in it will be…JEE Main 2021 (27 Jul, Shift 1)
An electromagnetic wave of frequency 5 GHz, is travelling in a medium whose relative…JEE Main 2021 (24 Feb, Shift 1)
An electromagnetic wave of frequency 3 GHz enters a dielectric medium of relative…JEE Main 2021 (24 Feb, Shift 2)
Electric field of plane electromagnetic wave propagating through a non-magnetic medium is…JEE Main 2021 (1 Sep, Shift 2)
For a transparent medium, relative permeability and permittivity, μr and εr are 1.0 and…NEET 2019
An electromagnetic wave of intensity 50 Wm–2 enters in a medium of refractive index 'n'…JEE Main 2019 (11 Jan, Shift 1)

Speed of EM Waves in a Medium question from JEE Main 2022 (28 Jun, Shift 1)

More questions on Speed of EM Waves in a Medium