# Homework Help: Charge-to mass ratio

1. Jun 1, 2010

### justgroovin

1. The problem statement, all variables and given/known data
1.Sketch a diagram of the atom He3, using the appropriate quarks and leptons.

2 The charge-to-mass ratio of the pion was determined in 1. The charge-to-mass ratio of the electron is 1.76 x 10^11 C/kg.
a) Based on this info, predict which particle has a greater mass- the electron of the pion . Justify your answer by referring to the charge-to-mass ratio.
b) Use the value of the elementary charge (e = 1.6 x 10^-19C) to calculate the mass of the pion in kg. Compare the mass of the pion to the mass of the electron.

2. Relevant equations
q = q/m x m

3. The attempt at a solution
1. No problems, just stated question to illustrate entire problem

2a) I predict the He3 particle will have more mass- it consists of 2 protons, 1 neutron and 2 electrons

2b) mass of electron = charge/ charge to mass ratio
= (1.6 x 10^(-19) C)/(1.76 x 10^11 C/kg)
= 9.09 x 10-31 kg
It's the pion charge-to-mass ratio I'm having troubles with. Between the quarks and leptons- it is a neutral atom, therefore dividing the charge by the mass is 0
I feel like I've been at this too long, and I'm missing a basic point here.

Last edited: Jun 1, 2010
2. Jun 1, 2010

### Dickfore

There is not enough information to formulate an intelligible reply.

3. Jun 2, 2010

### RoyalCat

The Pion is not an atom, it is a meson.

Pions can have ±1 elementary charge. That is the charge to mass ratio the question is referring to. This is something you should have, according to the question.

4. Jun 2, 2010

### justgroovin

So the pion is a meson of the He3 atom?
Can't pions also have a 0 charge? +1, -1 or 0 charge?

5. Jun 2, 2010

### justgroovin

The charge-to-mass ratio was not provided. It was to be determined trhrough my sketch in #1. The sketch shows that the quarks and leptons cancel each other out to leave the meson with a 0 charge

6. Jun 2, 2010

### RoyalCat

How does sketching a He3 atom provide you with data on a pion?

Consider the following, there are three kinds of pions, $$\pi ^ 0, \pi ^{-}, \pi^{+}$$

7. Jun 2, 2010

### justgroovin

I figured that since it helped me to see that the quarks and leptons cancel out each other, it shows a 0 charge. Since the ratio is q/m and q = 0 then the ratio = 0.

8. Jun 2, 2010

### Dickfore

How exactly is this equation supposed to help solve the problem?

9. Jun 2, 2010

### justgroovin

mass = charge/ charge to mass ratio
is what I got from that equation, and I used this to help me determine the mass of the electron.
I am supposed to compare the mass of pion to the mass of the electron, so I needed to determine the mass of the electron.

10. Jun 2, 2010

### justgroovin

This is my final question in my ILC course (other than my unit summary) before I prep for my final. I haven't NOT answered any questions yet, and I could really use some help to understand what I'm just not getting about this one.