The figure shows a region of length '$\ell$' with a uniform magnetic field of 0.3 T in it and a proton entering

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The figure shows a region of length '$\ell$' with a uniform magnetic field of 0.3 T in it and a proton entering the region with velocity 4×105 ms-1 making an angle 60º with the field. If the proton completes 10 revolution by the time it cross the region shown, '$\ell$' is close to (mass of proton = 1.67 × 10-27 kg , charge of the proton = 1.6 × 10-19 C)

(1) 0.22 m

(2) 0.88 m

(3) 0.44 m

(4) 0.11 m