Lorentz Force Law, am i messing up vector algebra?

In summary, the problem involves an electron with an initial velocity and constant acceleration in the presence of uniform electric and magnetic fields. The question is asking to find the electric field, given that the magnetic field is 400 µT and the equation for electric field is given in units of V/m. The incorrect answer may be due to rounding errors and it is important to use the full calculator value for accurate calculations. It should also be noted that electrons have a negative charge, which should be taken into account in the equation.
  • #1
mr_coffee
1,629
1
Okay here is my work:
http://show.imagehosting.us/show/891312/0/nouser_891/T0_-1_891312.jpg
and here is my calculations part:
http://img136.imageshack.us/img136/5539/lastscan7qc.jpg
Problem says:
14. [HRW7 28.P.008.] An electron has an initial velocity of (14.0 j + 21.0 k) km/s and a constant acceleration of (3.50 10^12 m/s2) i in a region in which uniform electric and magnetic fields are present. If B = (400 µT) i, find the electric field E.
V/m i + V/m j + V/m k

I know I'm getting the wrong answer because i tried to submit the i component and it was wrong i got:
19.88i

any ideas where i screwed up?
 
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  • #2
I haven't really done the question here, but from the looks of it you have rounded your values incorrectly. Are you using the full calculator value in your calculation though? If so then it doesn't matter, but if you're using rounded values then your answer might just be out by a little. You're using SI units throughout so you definitely have V/m as your final unit.
 
  • #3
last time I checked, electrons had charge negative (-) e !
 
  • #4
so u don't use the magntiude of the charge in that equation?
 

Related to Lorentz Force Law, am i messing up vector algebra?

1. What is the Lorentz Force Law and how does it relate to vector algebra?

The Lorentz Force Law is a fundamental law of electromagnetism that describes the force exerted on a charged particle moving through a magnetic field. It is given by the equation F = q(E + v x B), where q is the charge of the particle, E is the electric field, v is the velocity of the particle, and B is the magnetic field. This equation involves vector algebra because the force, electric field, and magnetic field are all vector quantities with both magnitude and direction.

2. How do I know if I am correctly applying vector algebra in the Lorentz Force Law?

To ensure you are correctly applying vector algebra in the Lorentz Force Law, you should pay attention to the direction of each vector. The electric field and magnetic field are typically given in the problem and have known directions, while the velocity of the particle may also have a known direction or can be determined from the problem. Make sure to take into account the cross product (v x B) and the resulting direction of the force vector.

3. Can the Lorentz Force Law be used to calculate the force on a stationary charged particle?

No, the Lorentz Force Law only applies to charged particles that are in motion. If a particle is stationary, there is no velocity term in the equation and the force would be zero. Additionally, the Lorentz Force Law only applies to charged particles, so it cannot be used to calculate the force on neutral objects.

4. How does the Lorentz Force Law explain the motion of charged particles in a magnetic field?

The Lorentz Force Law explains the motion of charged particles in a magnetic field by showing that the force on a charged particle is always perpendicular to both its velocity and the magnetic field. This means that the particle will experience a circular motion if the magnetic field is constant, or a helical motion if the magnetic field is non-uniform.

5. What other applications does the Lorentz Force Law have?

The Lorentz Force Law has a wide range of applications in various fields, such as particle accelerators, mass spectrometry, and magnetic levitation. It is also used in the study of plasma physics, where charged particles interact with electromagnetic fields. Additionally, the Lorentz Force Law is a key principle in the design and operation of many electrical and electronic devices, such as motors, generators, and transformers.

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