In an experimental technique for treating deep tumors, unstable positively charged pions (π + , elementary particles with a mass of 2.25×10−28kg) penetrate the flesh and disintegrate at the tumor site, releasing energy to kill cancer cells. If pions with a kinetic energy of 8 keV are required and if a velocity selector with an electric field strength of 2.2×103 V/m is used, what must be the magnetic field strength?

7.12*10^-4 T

Explanation:

Given

Mass of particles, m = 2.25*10^-28 kg

Energy of the pions, E = 8 keV

Electric field strength, B = 2.2*10^3 V/m

To start with, we know that

K = 1/2*m*v² if we make v subject of formula, we have

v = √(2K/m) if we substitute our values, we get

v = √[(2 * 8 * 1.6*10^-16) / 2.25*10^-28

v = √(2.56*10^-15 / 2.25*10^-28)

v = √1.137*10^13

v = 3.37*10^6

The velocity selector is

v = E/B, Making B subject of formula, so

B = E/v

B = 2.40x10^3 / 3.37*10^6

B = 7.12*10^-4 T

Thus, the magnetic field strength must be 7.12*10^-4 T

= 6.36x10^-4T

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.