Jack H.

Sketch qualitatively the electric field lines both between and outside two concentric conducting spherical shells when a uniform positive charge $q_{1}$ is on the inner shell and a uniform negative charge $-q_{2}$ is on the outer. Consider the cases $q_{1}>q_{2}, q_{1}=q_{2},$ and $q_{1}<q_{2}$

The nucleus of a plutonium- 239 atom contains 94 protons. Assume that the nucleus is a sphere with radius 6.64 $\mathrm{fm}$ and with
the charge of the protons uniformly spread through the sphere. At
the surface of the nucleus, what are the (a) magnitude and (b) direction (radially inward or outward) of the electric field produced by the protons?

An electron that has an instantaneous velocity of $$
\vec{v}=\left(2.0 \times 10^{6} \mathrm{m} / \mathrm{s}\right) \hat{\mathrm{i}}+\left(3.0 \times 10^{6} \mathrm{m} / \mathrm{s}\right) \hat{\mathrm{j}}
$$ is moving through the uniform magnetic field $\vec{B}=(0.030 \mathrm{T}) \hat{\mathrm{i}}-$
$(0.15 \mathrm{T}) \hat{\mathrm{j}} .(\mathrm{a})$ Find the force on the electron due to the magnetic
field. (b) Repeat your calculation for a proton having the same
velocity.

An electron moves through a uniform magnetic field given by $\vec{B}=B_{x} \hat{i}+\left(3.0 B_{x}\right) \hat{\mathrm{j}}$ . At a particular instant, the electron has velocity $v=(2.0 \hat{\mathrm{i}}+4.0 \hat{\mathrm{J}}) \mathrm{m} / \mathrm{s}$ and the magnetic force acting on it is $\left(6.4 \times 10^{-19} \mathrm{N}\right) \hat{\mathrm{k}} .$ Find $B_{x}$

An electron has an initial velocity of $(12.0 \hat{\mathrm{j}}+15.0 \hat{\mathrm{k}}) \mathrm{km} / \mathrm{s}$ and a constant acceleration of $\left(2.00 \times 10^{12} \mathrm{m} / \mathrm{s}^{2}\right) \hat{\mathrm{in}}$ a region in which
uniform electric and magnetic fields are present. If $B=(400 \mu \mathrm{T}) \hat{\mathrm{i}}$ ,
find the electric field $\vec{E} .$

An ion source is producing $^{6}$ Li ions, which have charge $+e$ and mass $9.99 \times 10^{-27} \mathrm{kg}$ . The ions are accelerated by a potential
difference of 10 $\mathrm{kV}$ and pass horizontally into a region in which there is a uniform vertical magnetic field of magnitude $B=1.2 \mathrm{T}$ . Calculate the strength of the smallest electric field, to be set up over the same region, that will allow the $^{6} \mathrm{L}$ i ions to pass through
undeflected.