Answer to Question #175999 in Electric Circuits for Peter green

Question

An electron (m=9.11*10^ -31 kg,q=1.60*10^ -19 C) rest is accelerated through an electric potential difference of 12.0V. then enters a uniform magnetic field of 0.100 T (up), when initially moving (N)

a) Find the initial speed of the electron entering the magnetic field.

b) Find the magnetic force on the electron entering the magnetic field.

c) Find the radius of the circular path of the electron in the field .

Answer 1

Mass of electron(m) = $9.11\times10^{-31}\space kg$

Charge of an electron(q) = $1.6\times10^{-19}\space C$

Magnetic Field(B) = $0.100 \space T$

Potential Difference(V) = $12\space V$

(a) Initial velocity of electron = $u\space$ m/s

$\dfrac{1}{2}mu^2=eV$

$\Rightarrow u=\sqrt{\dfrac{2eV}{m}}$

$\Rightarrow u=2.06\times10^6\space m/s$

(b) $F=qvBsin\theta$

$\Rightarrow F=1.6\times10^{-19}\times2.06\times 10^6\times0.100\times sin90\degree$

$\Rightarrow F=3.296\times10^{-14}\space N$

(c) $r=mvqBsin\theta$

$\Rightarrow r=2.99\times10^{-44}\space m$