# Tutor profile: Rajat N.

## Questions

### Subject: Electrical Engineering

What will happen if we connect a DC shunt motor's windings directly to a battery without a commutator?

Since commutator is absent, the direction of current in the windings will not reverse. Therefore the magnetic force will always act in one direction. hence the rotor will only oscillate and no rotation takes place.

### Subject: Physics

Let a charged particle moves with a velocity v near a current carrying conductor. So, a magnetic force acts on it. If the same particle is seen from a frame moving with velocity v in the same direction, the charge will be found to be at rest. Will the magnetic force become zero in this frame? Will the magnetic field become zero in this frame?

Magnetic force becomes zero as the particle is at rest in this frame of reference and we know that force on a particle is given by the cross product of Mag. Field and Velocity. As relative velocity is zero, Force is also zero. But magnetic field on the particles still exists because the current is independent of the frame of reference. For any reason, if the electrons of the wire seem to be at rest in a frame of reference, the protons are still flowing opposite to the frame of reference. Due to this, the current and the magnetic fields still exist.

### Subject: Algebra

What is the number of digits in 2^64?

log (2^64) = 64 x log (2) we know that log (2) = 0.303 therefore, 64 x log (2) = 19.266 It's characteristic is 19. Hence no. of digits in 2^64 is 20.

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