Magnetic Field homework

In summary: For similar problems, you can post a new thread.In summary, the conversation was about a cross section of a thin ribbon carrying a current, and the question was about the magnetic field at a point in the plane of the ribbon. The attempted solution involved using the Biot-Savart law, but the final answer was incorrect. The conversation ended with one person figuring out the solution but not specifying the exact equation used.
  • #1
Amy Marie
13
0

Homework Statement


Figure 29-61 shows a cross section of a long thin ribbon of width w = 4.91 cm that is carrying a uniformly distributed total current i = 4.61 * 10^-6 A into the page. What is the magnetic field at a point in the plane of the ribbon at a distance 2.16 cm from its edge?

Homework Equations


B = ((1.26 * 10^-6)i)/(2*pi*R)

The Attempt at a Solution


I tried using the Biot-Savart law:

0.0491 m + 0.0216 m = 0.0707 m

((1.26 * 10^-6)(4.61 * 10^-6))/(2*pi*0.0707) = 1.3 * 10^-11 T

((1.26* 10^-6)(4.61 * 10^-6))/(2*pi*0.0216) = 4.28 * 10^-11 T

(4.28 * 10^-11) - (1.3 * 10^-11) = 2.98 * 10^-11 T

When I checked, the answer was 22.3 pT instead of 29.8 pT.
Can anybody please let me know what I should be doing differently?
 
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  • #2
I don't understand your calculations.
Amy Marie said:
((1.26 * 10^-6)(4.61 * 10^-6))/(2*pi*0.0707) = 1.3 * 10^-11 T
This is the field 2.16cm outside, okay. The units are missing.
Amy Marie said:
((1.26* 10^-6)(4.61 * 10^-6))/(2*pi*0.0216) = 4.28 * 10^-11 T
What is this?
And where is the point in subtracting the two values?

Does the question really ask for a point outside? That would make the details about the ribbon pointless.
 
  • #3
mfb said:
I don't understand your calculations.This is the field 2.16cm outside, okay. The units are missing.
What is this?
And where is the point in subtracting the two values?

Does the question really ask for a point outside? That would make the details about the ribbon pointless.
I figured the problem out, but thank you.
 
  • #4
Amy Marie said:
I figured the problem out, but thank you.
how did you solve it
using what equation
 
  • #5
This thread is from 2014 and OP didn't post anything in this forum in the last three years, it is unlikely that you will get an answer.
 

1. What is a magnetic field?

A magnetic field is an invisible area around a magnet or electric current where magnetic forces can be detected. It is created by the movement of charged particles and can exert a force on other magnets or charged particles in its vicinity.

2. How is the strength of a magnetic field measured?

The strength of a magnetic field is measured in units called tesla (T) or gauss (G). One tesla is equal to 10,000 gauss. This measurement is usually taken with a device called a magnetometer.

3. What factors affect the strength of a magnetic field?

The strength of a magnetic field can be affected by the distance from the source, the orientation of the magnetic field lines, and the strength of the source, such as a magnet or electric current. Additionally, the type of material the magnetic field is passing through can also impact its strength.

4. What are some real-life applications of magnetic fields?

Magnetic fields have a wide range of applications in our daily lives. They are used in generators to produce electricity, in motors to convert electricity into motion, in MRI machines for medical imaging, in speakers and headphones for sound production, and in compasses for navigation, just to name a few.

5. How do magnetic fields affect living organisms?

While magnetic fields do not have a direct impact on living organisms, they can have an indirect effect on them. For example, many animals, such as birds, use the Earth's magnetic field for navigation during migration. Strong magnetic fields can also disrupt the navigation systems of some animals, causing disorientation and other behavioral changes.

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