An electron is accelerated from rest through a potential difference of and then…

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism

Problem

An electron is accelerated from rest through a potential difference of

200\,\text{V}

and then enters a region of uniform magnetic field

B_1=0.30\,\text{T}

, moving perpendicular to the field lines and describing a circle of radius

r

. If the accelerating potential is increased to

800\,\text{V}

and the same radius

r

is to be maintained, what should be the new magnetic field

B_2

? (a)

0.30\,\text{T}

(b)

0.60\,\text{T}

(c)

1.20\,\text{T}

(d)

0.15\,\text{T}