Pic A proton (mass= 1.67×10-27 kg, charge= 1.6×10-19 C) travelling with speed 1×106 m/s enters a region of space containing a uniform magnetic field of 1.2 T. What is the time t required for the proton to re-emerge into the field-free region? t =

Complete Question

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The time t required is

Explanation:

When this proton move into the magnetic field region the magnetic field would cause it to move in a clockwise direction

   The force which it would feel inside the field is mathematically denoted as follows

And this is the same thing as the force which keeps it around the circle without spiraling off and this is also know as centripetal force and it is mathematically

Since the two force are equal we can equate the formulas

making r the subject of the formula

Now mathematically the total distance traveled is  

Since  

                    =  

real, smaller and upside-down.   so the answer should be b.