Worksheet: Force on Conducting Wires in Magnetic Fields

In this worksheet, we will practice using the formula F = BIL to calculate the force experienced by a current-carrying wire that has been placed in a uniform magnetic field.

Q1:

A 50 cm current-carrying section of wire is positioned at 9 0 to a 0.2 T magnetic field. It experiences a force of 0.25 N. What is the strength of the electric current in the wire?

Q2:

The diagram shows a section of wire that has been positioned parallel to a uniform 0.1 T magnetic field. The wire carries a current of 2 A. What is the direction of the force acting on the wire due to the magnetic field?

  • AInto the screen
  • BOut of the screen
  • CUp the screen
  • DThere is no force acting on the wire.
  • EDown the screen

Q3:

The diagram shows a section of wire that has been positioned at to a 0.1 T magnetic field. The wire carries a current of 2 A. What is the direction of the force acting on the wire due to the magnetic field?

  • ATo the right
  • BInto the screen
  • CTo the left
  • DOut of the screen
  • EThere is no force acting on the wire.

Q4:

When positioned at 9 0 to a magnetic field, a wire of length 1 m carrying a current of 4 A experiences a force of 0.2 N. What is the strength of the magnetic field?

Q5:

A 20 cm section of wire carrying a current of 12 A is positioned at 9 0 to a 0.1 T magnetic field. What is the size of the force acting on the wire?

Q6:

Which of the following is the correct formula for the magnitude of the force experienced by a current-carrying wire in a uniform magnetic field? 𝐹 is the force experienced by the wire, 𝑎 is the acceleration of the wire, 𝐿 is the length of the wire, 𝐼 is the magnitude of the current within the wire, and 𝐵 is the strength of the magnetic field.

  • A 𝐹 = 𝐵 𝐼 𝐿 2
  • B 𝐹 = 𝐵 𝐼 𝐿
  • C 𝐹 = 𝐵 𝐼 𝐿
  • D 𝐹 = 𝐵 𝐼 𝐿
  • E 𝑎 = 2 𝐵 𝐼 𝐿

Q7:

What is 40 millitesla in tesla?

Q8:

Which of the following is the correct unit for the strength of a magnetic field?

  • AJoule
  • BWatt
  • CCoulomb
  • DTesla
  • ENewton

Q9:

The diagram shows a square section of a wire that has been positioned in a uniform magnetic field such that two of its sides are perpendicular to the direction of the field and the other two sides are parallel to the field. The magnetic field has a strength of 0.3 T, and the current through the wire is 2 A. Each side of the square is 0.2 m long.

What is the magnitude of the force acting on the right-hand side of the square?

Initially, what is the direction of the force acting on the right-hand side of the square?

  • AOut of the screen
  • BInto the screen

What is the magnitude of the force acting on the left-hand side of the square?

Initially, what is the direction of the force acting on the left-hand side of the square?

  • AOut of the screen
  • BInto the screen

What is the magnitude of the force acting on the top side of the square?

What is the overall effect of the magnetic field on the wire?

  • AThe magnetic field accelerates the wire out of the screen.
  • BThe magnetic field has no overall effect on the wire.
  • CThe magnetic field makes the wire spin about the 𝑥 -axis of the screen.
  • DThe magnetic field makes the wire spin about the 𝑦 -axis of the screen.
  • EThe magnetic field accelerates the wire into the screen.

Q10:

A 0.5 m long section of wire carrying a current of 12 A is positioned at 9 0 to a magnetic field. The mass of the wire is 15 g. What must the strength of the magnetic field be in order to counteract the weight of the wire? Use a value of 9.8 m/s2 for the acceleration due to gravity.

Q11:

A 1 m long wire carrying a current of 5 A is positioned at 9 0 to a 0.1 T magnetic field. The mass of the wire is 25 g. How quickly does the wire accelerate?

Q12:

The diagram shows a square section of wire that has been positioned in a uniform magnetic field such that two of its sides are perpendicular to the direction of the field and the other two sides are parallel to the field. The magnetic field has a strength of 0.2 T, and the current through the wire is 5 A. Each side of the square is 0.1 m long.

What is the torque exerted on the wire by the magnetic field?

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