A positron with kinetic energy 2.30 keV is projected into a uniform magnetic field of magnitude 0.0980 T, with its velocity vector making an angle of 82.0° with the field. Find (a) the period, (b) the pitch p, and (c) the radius r of its helical path.

Respuesta :

Answer:

a)0.364 ns

b)1.43 x 10^-3

c)163.21 x 10^-5 m

Explanation:

mass of the positron is m=9.1 x 10^-31 kg

charge is q=1.6 x 10^-19 C

strength of the magnetic field is B=0.0980 T

kinetic energy is K=2.30 keV=2.30 x 10^3 x 1.6 x 10^-19 J

0.5mv^2=6.68 x 10^-16 J

0.5 x 9.1 x 10^-31 x v^2 =3.68 x 10^-16

v=2.84 x 10^7 m/s

a)the period is T=2πm/qB

                         =2π(9.1 x 10^-31 )/1.6 x 10^-19x 0.0980

                         =0.364 ns

b) pitch is p=vcosθ(2πm/qB)

                  =2.84 x 10^7x cos82(0.364 x 10^-9)

                  =1.43 x 10^-3

c) radius is r=mvsinθ/qB

                  =(9.1 x 10^-31 )2.84 x 10^7x sin82/1.6 x 10^-19x 0.098

                   =163.21 x 10^-5 m

Answer:

a) period = 0.364 ns

b) pitch  [tex]=1.44 \times 10^{-3}[/tex]

c) radius [tex] =1.63 \times 10^{-3} m[/tex]

Explanation:

Given data:

mass of the positron is [tex]m = 9.1 \times 10^{-31} kg=[/tex]

charge is [tex]q = 1.6 \times 10^{-19}C[/tex]

strength of the magnetic field is B = 0.0980 T

kinetic energy is [tex]K=2.30 keV = 2.30 \times 10^3 \times 1.6 \times 10^{-19}J[/tex]

[tex]0.5mv^2 = 3.68 \times 10^{-16} J[/tex]

[tex]0.5 \times 9.1 \times 10^{-31} \times v^2 = 3.68 x 10^{-16}[/tex]

[tex]v= 2.843 \times 10^7m/s[/tex]

a) period is [tex]T=\frac{2πm}{qB}[/tex]

                         [tex]=\frac{2π(9.1 \times 10^{-31})}{1.6 \times 10{-19}\times 0.0980}[/tex]

                         =0.364 ns

b)pitch is [tex]p = vcos\theta \frac{(2πm}{qB})[/tex]

                  [tex]=2.843 \times 10^7 \times cos82(0.3646 \times 10^{-9})[/tex]

[tex]=1.44 \times 10^{-3}[/tex]

c) radius is [tex]r = \frac{mvsin\theta}{qB}[/tex]

                  [tex]=\frac{(9.1 \times 10^{-31})\times 2.843 \times 10^7\times sin 82}{1.6 \times 10^{-19}\times 0.0980}[/tex]

                  [tex] =1.63 \times 10^{-3} m[/tex]