Calculating Magnetic Forces on Moving Charges in a Magnetic Field

[silentcoder]

Homework Statement

1. Determine the magnetic force acting on an proton (m = 1.67 x 10-27 kg) moving at 2.9 x 106 m/s in a magnetic field of 6.8 T. The proton is moving south. The magnetic field points straight down.

2. A 6.0 m long wire with 7.0A of current flowing through it experiences a force of 12 N. Determine the magnitude of the magnetic field. You may assume that the current and the magnetic field are 90° to one another.

Homework Equations

1. Fm = qvbsinƟ
2. Fm = IlBsinƟ

The Attempt at a Solution

1. There was no charge given so is it alright to use charge of 1.6x10^-19?
Fm = qvbsinƟ
Fm = (1.6x10^-19 C)(2.9x10^6 m/s)(6.8T) sin 90
Fm = 2.53 x 10^-12 N

2. No magnetic field strength is given so how can i figure out the magnetic field strength?

Thanks

 

[SC400slide]

I would love to know as well...

 

[rude man]

Homework Statement

1. Determine the magnetic force acting on an proton (m = 1.67 x 10-27 kg) moving at 2.9 x 106 m/s in a magnetic field of 6.8 T. The proton is moving south. The magnetic field points straight down.

2. A 6.0 m long wire with 7.0A of current flowing through it experiences a force of 12 N. Determine the magnitude of the magnetic field. You may assume that the current and the magnetic field are 90° to one another.

Homework Equations

1. Fm = qvbsinƟ
2. Fm = IlBsinƟ

The Attempt at a Solution

1. There was no charge given so is it alright to use charge of 1.6x10^-19?

Yes. A proton has charge = electron but + instead of -.

Fm = qvbsinƟ
Fm = (1.6x10^-19 C)(2.9x10^6 m/s)(6.8T) sin 90
Fm = 2.53 x 10^-12 N

2. No magnetic field strength is given so how can i figure out the magnetic field strength?

Thanks

What is the force on a wire of length L in a B field if the B field is orthogonal to the wire? Very basic formula ...

 

[silentcoder]

For number 1 i get: Fm = -3.15x10^-12 N[South]

For number 2 I am having hard time understanding what you are trying to say.

 

[rude man]

For number 1 i get: Fm = -3.15x10^-12 N[South]

For number 2 I am having hard time understanding what you are trying to say.

If you'll try to answer my question ... I should have added, the wire has a current i flowing thru it.

 

[silentcoder]

If you'll try to answer my question ...

The formula will be F = ILB SinƟ

This is what I get:
F = ILB sin 90
12 N = (7.0 A)(6.0 m)B sin 90
12 N/(7.0 A)(6.0 m) = B sin 90
2/7 = B sin 90
B = 2/7 T
B = 0.29 T

 

[rude man]

The formula will be F = ILB SinƟ

This is what I get:
F = ILB sin 90
12 N = (7.0 A)(6.0 m)B sin 90
12 N/(7.0 A)(6.0 m) = B sin 90
2/7 = B sin 90
B = 2/7 T
B = 0.29 T

Looking good ...

 

[silentcoder]

Looking good ...

Thanks so were those 2 questions correct?

 

[rude man]

I did not check your numbers but the formulas were correct.