## Carrying Homework Picture

1. An electron enters a 4.0 T field with a velocity of 5.0 x 10^{5} m/s perpendicular to the field. What is the radius of curvature of its path?

3. A wire with a linear density of 1 g/cm moves horizontally to the north on a horizontal surface with a coefficient of friction 0.2. What are the magnitude and the direction of the smallest magnetic field that enables the wire to continue in this fashion?

4. An electron is accelerated from rest through a potential difference of 18 kV, and then passes through a 0.34-T magnetic field. Calculate the magnitude of the maximum magnetic force acting on the electron.

5. A 0.0017 T magnetic field and a 5.7 x 10^{3} N/C electric field both point in the same direction. A positive 2.0-mC charge moves at a speed of 2.9 x 10^{6} m/s perpendicular to both fields. Determine the magnitude of the net force on the charge.

6. What is the magnitude of the magnetic force on an electron moving 5.0 x 10^{4} m/s perpendicular to a uniform magnetic field of .20T?

7. What speed would a proton need to orbit 1000 km above the Earth along the magnetic equator where the magnetic field intensity is 4.00x10^{-8} T?

8. a. Find the magnetic flux density 3.1 mm away from a long straight wire carrying a 1.2 A current.

b. What force per meter would act on a long straight wire 3.1mm away from and parallel to the wire in part (a) and carrying a 4.5A current?

c. What force would act on a 37 μC charged particle 3.1mm from the wire in part (a) and moving away from the wire at 6.5 m/s?

9. Find the magnetic flux density in the center of a 4.0 cm long air-core solenoid made with 4900 turns of wire and carrying a 2.5A current.

10. Express the attenuation distance for a plane electromagnetic wave in a good conductor in terms of the conductivity *σ*, permeability *μ*_{0}, and frequency *ω*.

2. A conducting rod of 25 cm is pushed across a magnetic field along a U-shaped wire at a constant speed of 2.0 m/s. The field is directed away from the observer and is 4.00 T. A current of 8.00 A is induced in the circuit.

a. What is the potential difference induced in the circuit?

b. What is the resistance of the circuit?

c. What is the force used to push the rod?

d. In what direction is current flowing in the rod?

In Fig, there are an infinitely long conductive wire and a circle conductive loop C with the radius r and the number of turns n. The distance L between the wire and the loop is much larger than r, i.e., L >> r. The normal direction of the loop is x and the current I flows through the wire downwards. Under this condition, We want the magnetic field intensity due to I through the loop C to enhance. How should we make a current flow in the loop C? Draw the answer schematically in the answer sheet.

**Now I have done some work on this question but it still wrong. my work is given below.**

**Answer**

Problem-1: From eq(1) we can see that magnetic flux Φ_B depends upon the distance L between a loop and a current carrying long wire. So decreasing the value of L magnetic field intensity can be enhanced. [Since I is constant then we only have to change L to enhance the magnetic field intensity.] Problem-2: If the current I through the infinite conductive wire is fixed and length L is also fixed, then we can make a current flow in the loop C (which must be a closed loop) by rotating it in y axis as shown in figure 4.1 and figure 4.2. Since according to Faraday's law, emf is induced in a closed loop of wire when magnetic flux linkage changes. That is, current flows through the closed loop. If there is no change (with time) in the number of lines of B field, or magnetic flux, through a closed loop (C) there will be no induced voltage set up as well as current in the loop.

**But this far I am able to go. In general text book, the loop circuit is drawn as only a circle without a buttery, but in some text book, for simply, a circuit is only a loop wire. Current flowing is indicated by an arrow with the direction, which is nearby the loop. And also, the loop is connected with a buttery. But. the buttery is not shown in the figure because this is common in this study field.**

*how can i solve this problem*

homework-and-exerciseselectromagnetism

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