How do I calculate current, power, and force in a circuit with given variables?

  • Thread starter KingJaymz
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In summary, the conversation discussed a problem involving standing on train tracks with a lamp and a train approaching. The calculations were done to find the current, power, and force in the circuit using equations such as "emf = Blv", "V = IR", and "P = VI". The calculated values were 3.6 X 10^-2 V, 8.0 X 10^-4 A, and 2.88 X 10^-5 W, respectively. However, there was a decimal point error in the initial calculation, which affected the other values. The correct value for emf is 3.6 X 10^-3 V. The conversation ended with a thank you for pointing out the error and
  • #1
KingJaymz
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Hello, I've done all of the calculations on my homework assignment and have gotten what seem to be the mathematically correct answers, but I'm not sure that they logically make sense. This is the diagram and the problem:
diagram.jpg


You are standing on train tracks in such a way that a circuit is completed. You have a lamp in your hands that has an internal resistance of 45 ohms. The track rails are 1.2 meters apart and the magnetic field is coming out of the page with a magnitude of 10^-5 Tesla. There is a train approaching at a velocity of 300 m/s. Find the current in the circuit, the total power used in the circuit and the force exerted on the train.

So I calculated the voltage with the equation "emf = Blv". Is this correct? For an answer, I got 3.6 X 10^-2 V.

To find the current, I used the proper form of "V = IR" and got an answer of 8.0 X 10^-4 A.

In order to calculate the power, I used "P = VI" and used the Voltage and Current values that I had already calculated.
This yielded 2.88 X 10^-5 W.

Finally, I calculated the force using the proper form of the equation "P = Fv".
This required me to divide 2.88 X 10^-5 by 300, giving me 9.6 X 10^-8 N. I might not be thinking about this correctly, but that seems a bit small. Did I screw up somewhere?

Thank you, in advance.
 
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  • #2
Your methods look good to me. I think you did make a decimal point error in calculating the emf, which carries through to the other numbers.
 
  • #3
Thank you very much, especially for pointing out the error in my math. That's a big help.
 

1. What is the difference between electricity and magnetism?

Electricity and magnetism are two fundamental forces of nature, but they have different properties and effects. Electricity is the flow of charged particles, usually electrons, through a conductor. Magnetism, on the other hand, is a force that is exerted by certain materials, such as iron or nickel, on other materials. While electricity can produce a magnetic field, magnetism cannot produce an electric field.

2. How are electricity and magnetism related?

Electricity and magnetism are closely related and are often referred to as electromagnetism. This is because moving electric charges, such as electrons in a wire, produce a magnetic field, and a changing magnetic field can induce an electric current. This relationship is described by Maxwell's equations, which are a set of fundamental equations in electromagnetism.

3. What is the difference between AC and DC electricity?

AC (alternating current) and DC (direct current) are two types of electrical currents. AC electricity changes direction periodically, while DC electricity flows in one direction. AC electricity is used in most household appliances and is generated by power plants, while DC electricity is typically used in batteries and electronic devices.

4. What is the role of conductors and insulators in electricity?

Conductors are materials that allow electricity to flow through them easily, while insulators are materials that do not allow electricity to flow through them. This is because conductors have free electrons that can move easily, while insulators have tightly bound electrons that do not move easily. This property is important in determining how electricity is transmitted and used in various devices.

5. How do magnets work?

Magnets work by creating a magnetic field around them. This field exerts a force on other magnetic materials, causing them to either attract or repel each other. The strength of a magnet's field depends on the material it is made of and its shape. Magnets are commonly used in motors, generators, and various household objects such as refrigerator magnets.

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