Traveling at an initial speed of 1.5 x 106 m/s, a proton enters a region of constant magnetic field of magnitude 1.5 t. if the proton's initial velocity vector makes an angle of 30 with the magnetic field, compute the proton's speed 4 s after entering the magnetic field. 0 a. 5.0 x 105 m/s o b. 7.5 x 105 m/s ° c. 1.5 x 106 m/s 0 d. 3.0 x 106 m/s

C)

Explanation:

As we know that force on a moving charge due to magnetic field is given by

so from above formula we can see that

force on moving charge is always perpendicular to the velocity on charge moving in constant magnetic field

So the work done by this force on moving charge is always zero

so this force can change the direction of velocity of charge but it can not change the magnitude of speed of the charge

so at all instants of time the speed will remain the same

so after t = 4 s the speed of the charge is given as

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

i really dont know but i will try okay.

so i think u would just add all them up and get your answer..