An electron is accelerated from rest by an electric field. After the acceleration, the electron is injected into a uniform magnetic field of 1.27 times 10-3 T. The velocity of the electron and the magnetic field lines are perpendicular to one another. The electron remains in the magnetic field for 5.13 times 10-9 seconds. The angle (in radians) between the initial electron velocity and the final electron velocity is .

Explanation: the electron will move uniformly in circular path in magnetic field .

Let B be magnetic field , r be radius of circular path , v and ω be linear and angular velocity of electron , q and m  be charge on electron and mass of electron

centripetal force = magnetic force on electron

mω²r = B q v

mω² = B q (v / r)

mω² = B q ω

ω = B ( q / m )

= 1.27 x 10⁻³ x( 1.6 x 10⁻¹⁹ / 9.1 x 10⁻³¹ )

= .2233 x 10⁹ rad / s

angle of rotation by electrons

= angular velocity x time

= .2233 x 10⁹ x 5.13 x 10⁻⁹

= 1.145 radian .

need to see circuit to get time constant

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles