Engineering
Physics
Momentum and Energy Conservation for System of Particles
Communication Channel Mode of Communication Basic Terms and Block Diagram
Motion of Charged Particle in Uniform Magnetic Field
Question

A neutral particle is initially at rest in a uniform magnetic field B as shown in the diagram. The particle then spontaneously decays into two fragments, one with a positive charge +q and mass 3m and the other with a negative charge –q and mass m. Neglecting the interaction between the two charged particles and assuming that the speeds are much less than speed of light, determine the time (in µs) after the decay at which the two fragments first meet. (use the following data q = 1µC, B = 2πµT, m = 10–15 kg). Both the charges have initial velocities in x-y plane.

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Solution
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r=pqB=same, T+=2πm+qB=6πmqB, T=2πmqB
as T+ = 3T,  They will meet at θ =π/2                

q = 1 µC, B = 2πµT , m = 10–15 kg


The time is =T+4=6πm4qB=6×π×10154×1×106×2π×106
= 0.75 × 10–3 S = 750 µS