An electron moves in a circular path perpendicular to a magnetic field of magnitude 0.220 T. If the kinetic energy of the electron is 4.30 ✕ 10−19 J, find the speed of the electron and the radius of the circular path. (a) the speed of the electron m/s (b) the radius of the circular path µm

Explanation:

m = Mass of electron =

B = Magnetic field = 0.22 T

K = Kinetic energy of electron =

q = Charge =

v = Velocity of electron

r = Radius of curved path

Kinetic energy is given by

The speed of the electron is

The force balance of the system is given by

The radius of the curved path is

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.