Q: A wire of length $$0.5\ \mathrm{m}$$ carries a current of $$2\ \mathrm{A}$$ and is placed in a $$0.3\ \mathrm{T}$$ magnetic field at an angle of $$60^\circ to $$the field. What is the force on the wire?

$$F = I L B \sin \theta = 2 \times 0.5 \times 0.3 \times \sin 60^\circ = 0.26\ \mathrm{N}$$

Q: A wire of length $$2\ \mathrm{m} is $$placed in a $$0.5\ \mathrm{T}$$ magnetic field perpendicular to the wire. If the wire carries a current of $$3\ \mathrm{A}$$, what is the force on the wire?

$$F = 3\ \mathrm{A} \times 2\ \mathrm{m} \times 0.5\ \mathrm{T} = 3\ \mathrm{N}$$

Q: A wire of length $$0.25\ \mathrm{m}$$ carries a current of $$4.5\ \mathrm{A} in a$$ $$85\ \mathrm{mT}$$ magnetic field. What is the force if the wire is perpendicular to the field?

$$F = 4.5 \times 0.25 \times 0.085 = 0.096\ \mathrm{N}$$

Question 1

A straight wire of length $$L$$ carries a current $$I$$ and is placed in a uniform magnetic field $$B$$ such that the field is perpendicular to the wire. What is the magnitude of the force acting on the wire?

Accepted Answer

$$F = ILB$$

Question 2

A wire of length $$0.5\ \mathrm{m}$$ carries a current of $$2\ \mathrm{A}$$ and is placed in a $$0.3\ \mathrm{T}$$ magnetic field at an angle of $$60^\circ to $$the field. What is the force on the wire?

Accepted Answer

$$F = I L B \sin 	heta = 2 	imes 0.5 	imes 0.3 	imes \sin 60^\circ = 0.26\ \mathrm{N}$$

Question 3

Which of the following best describes the direction of the force on a current-carrying conductor in a magnetic field?

Accepted Answer

It is perpendicular to both the direction of current and the magnetic field, as given by the right-hand rule.

Question 4

A rectangular loop of wire with area $$A$$ and $$N$$ turns carries a current $$I$$ and is placed in a uniform magnetic field $$B. $$What is the maximum torque experienced by the loop?

Accepted Answer

$$	au_{max} = N I A B$$

Question 5

In a galvanometer, what physical principle allows the needle to deflect in response to an electric current?

Accepted Answer

The torque produced by the interaction of the current in the coil and the magnetic field.

Question 6

A wire of length $$2\ \mathrm{m} is $$placed in a $$0.5\ \mathrm{T}$$ magnetic field perpendicular to the wire. If the wire carries a current of $$3\ \mathrm{A}$$, what is the force on the wire?

Accepted Answer

$$F = 3\ \mathrm{A} 	imes 2\ \mathrm{m} 	imes 0.5\ \mathrm{T} = 3\ \mathrm{N}$$

Question 7

What is the Hall voltage $$V_H$$ developed across a conductor of width $$w$$ carrying current $$I in a $$perpendicular magnetic field $$B$$, given the charge carrier density $$n$$ and charge $$q$$?

Accepted Answer

$$V_H = \dfrac{B I}{n q w}$$

Question 8

Which of the following is a practical application of the Hall Effect?

Accepted Answer

Measuring the strength of a magnetic field.

Question 9

A current loop is placed in a uniform magnetic field. What happens to the loop?

Accepted Answer

It experiences a torque that tends to align the plane of the loop perpendicular to the magnetic field.

Question 10

In a DC electric motor, what is the function of the commutator?

Accepted Answer

It reverses the direction of current in the coil every half rotation to maintain continuous rotation.

Question 11

A wire of length $$L is $$carrying a current $$I$$ and is placed at an angle $$	heta to a $$uniform magnetic field $$B. $$What is the general formula for the magnetic force on the wire?

Accepted Answer

$$F = I L B \sin 	heta$$

Question 12

A circular coil with $$N$$ turns, area $$A$$, and current $$I is $$placed in a uniform magnetic field $$B$$ such that the normal to the coil makes an angle $$	heta$$ with the field. What is the torque on the coil?

Accepted Answer

$$	au = N I A B \sin 	heta$$

Question 13

Which of the following statements about the force between two perpendicular current-carrying wires is correct?

Accepted Answer

There is no net force, but there is a torque acting on the wires.

Question 14

A wire of length $$0.25\ \mathrm{m}$$ carries a current of $$4.5\ \mathrm{A} in a$$ $$85\ \mathrm{mT}$$ magnetic field. What is the force if the wire is perpendicular to the field?

Accepted Answer

$$F = 4.5 	imes 0.25 	imes 0.085 = 0.096\ \mathrm{N}$$

Question 15

Which of the following best explains why a current-carrying wire in a magnetic field experiences a force?

Accepted Answer

Moving charges in the wire interact with the magnetic field, resulting in a force perpendicular to both the current and the field.

Question 16

A single circular loop with a circumference of $$2.00\ \mathrm{m}$$ carries a current of $$17.0\ \mathrm{mA} in a$$ $$0.800\ \mathrm{T}$$ magnetic field. The field is parallel to the plane of the loop. What is the magnitude of the torque on the loop?

Accepted Answer

$$	au = IAB = 17.0 	imes 10$$^{-3}$$ 	imes 0.318 	imes 0.800 = 4.32 	imes 10$$^{-3}$$\ \mathrm{N \cdot m}$$

Magnetic Force on Current-Carrying Conductors and Applications

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