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A wire has a length of \(7.00 \times 10^{-2} \mathrm{m}\) and is used to make a circular coil of one turn. There is a current of \(4.30 \mathrm{A}\) in the wire. In the presence of a \(2.50-\mathrm{T}\) magnetic field, what is the maximum torque that this coil can experience?

Short Answer

Expert verified
The maximum torque is approximately \(2.66 \times 10^{-3} \, \text{Nm}\).

Step by step solution

01

Understand the Problem

We are dealing with a circular coil made of wire through which a current flows, and this coil is in a magnetic field. We need to calculate the maximum torque that the coil can experience.
02

Recall the Formula for Torque

The torque \(\tau\) on a current loop in a magnetic field is given by the formula: \(\tau = n \, I \, A \, B \, \sin(\theta)\), where \(n\) is the number of turns in the coil, \(I\) is the current, \(A\) is the area of the coil, \(B\) is the magnetic field strength, and \(\theta\) is the angle between the normal to the coil and the magnetic field vector. The torque is maximized when \(\sin(\theta) = 1\), which occurs when \(\theta = 90^\circ\).
03

Calculate the Radius of the Coil

Since the coil is a circle and made from a wire of length \(7.00 \times 10^{-2} \, \text{m}\), the circumference of the coil is equal to the length of the wire. The formula for the circumference of a circle is \(C = 2 \pi r\). Rearrange to find the radius: \(r = \frac{C}{2\pi} = \frac{7.00 \times 10^{-2}}{2\pi}\).
04

Calculate the Area of the Coil

The area \(A\) of a circle is given by \(A = \pi r^2\). Substitute \(r = \frac{7.00 \times 10^{-2}}{2\pi}\) into the area formula: \[A = \pi \left(\frac{7.00 \times 10^{-2}}{2\pi}\right)^2\].
05

Substitute Values into the Torque Formula

We now know that \(n = 1\), \(I = 4.30\, \text{A}\), \(A = \pi \left(\frac{7.00 \times 10^{-2}}{2\pi}\right)^2\), and \(B = 2.50\, \text{T}\). Substitute these into the torque formula assuming \(\sin(\theta) = 1\): \[\tau = 1 \times 4.30 \times \pi \left(\frac{7.00 \times 10^{-2}}{2\pi}\right)^2 \times 2.50\].
06

Perform the Calculation

Perform the calculation:\[\tau = 4.30 \times \pi \times \frac{(7.00 \times 10^{-2})^2}{4\pi^2} \times 2.50\] which simplifies to \[\tau = 4.30 \times \frac{(7.00 \times 10^{-2})^2}{4\pi} \times 2.50\] and gives \(\tau \approx 2.66 \times 10^{-3}\, \text{Nm}\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Circular Coil
A circular coil is essentially a loop of wire bent into the shape of a circle. In physics, this shape is important because the geometry of a circle allows functions like magnetic field and current to have distinct effects due to uniform distribution. In our exercise, the wire length is given as the circumference of the coil. This means we use the formula for the circumference of a circle, which is \( C = 2 \pi r \), where \( r \) is the radius. From this, we calculate the radius of our coil to understand the coil’s geometry.

After determining the radius, we can find the area of the coil using the formula \( A = \pi r^2 \). This area is crucial in calculating torque because it affects how the coil interacts with a magnetic field.
  • The coil here is a single turn; thus, \( n = 1 \).
  • Understanding the coil's geometry helps in calculating crucial parameters like area and circumference.
Magnetic Field
In physics, a magnetic field is a vector field that describes the magnetic influence of electric charges in relative motion and magnetized materials. In our problem, the magnetic field strength \( B \) is given as \( 2.50 \text{ T} \). T stands for Tesla, the unit of magnetic field strength. The magnetic field interacts with the electric current in the coil, producing what is known as the torque.

Strong magnetic fields exert greater forces on charged particles and current loops. When we consider this interaction for calculating torque, the direction and magnitude of the magnetic field are crucial factors.
  • A greater magnetic field results in more substantial torque acting on the coil.
  • Magnetic field lines are typically represented as vector quantities, influencing various elements like current loops and charged particles.
Current Loop
A current loop is simply a closed circuit in which an electric current flows. In our exercise, the current of \( 4.30 \text{ A} \) flows through a wire loop (the coil). This flow of current in a loop results in magnetic effects, creating its own magnetic field which interacts with the external magnetic field applied.

The interaction of the current loop with the external magnetic field is what gives rise to torque. The key components affecting this include:
  • The current's strength: A higher current increases the torque's magnitude.
  • The shape and area of the loop: A circular loop maximizes the effects due to symmetric distribution of forces.
Understanding how the current affects its surroundings helps to appreciate the induced electromagnetic effects like torque.
Maximum Torque
Torque refers to the rotational force experienced by an object about an axis. In this exercise, we need to find the maximum torque exerted by a circular coil in a magnetic field. The formula used is \( \tau = n \times I \times A \times B \times \sin(\theta) \).

Maximum torque is achieved when \( \theta = 90^\circ \), making \( \sin(\theta) = 1 \). This implies the coil and the magnetic field are perpendicular, optimizing the rotational force.
  • Maximum torque occurs when the coil’s plane is perpendicular to the field, maximizing interaction.
  • For maximum efficiency, ensuring alignment in this manner is critical in practical applications like motors and generators.
By fully understanding the conditions for maximum torque, designing devices for optimal performance becomes easier.

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Most popular questions from this chapter

A horizontal wire is hung from the ceiling of a room by two massless strings. The wire has a length of \(0.20 \mathrm{m}\) and a mass of \(0.080 \mathrm{kg} .\) A uniform magnetic field of magnitude 0.070 T is directed from the ceiling to the floor. When a current of \(I=42\) A exists in the wire, the wire swings upward and, at equilibrium, makes an angle \(\phi\) with respect to the vertical, as the drawing shows. Find (a) the angle \(\phi\) and (b) the tension in each of the two strings.

A positively charged particle of mass \(7.2 \times 10^{-8} \mathrm{kg}\) is traveling due east with a speed of \(85 \mathrm{m} / \mathrm{s}\) and enters a \(0.31-\mathrm{T}\) uniform magnetic field. The particle moves through one- quarter of a circle in a time of \(2.2 \times 10^{-3} \mathrm{s},\) at which time it leaves the field heading due south. All during the motion the particle moves perpendicular to the magnetic field. (a) What is the magnitude of the magnetic force acting on the particle? (b) Determine the magnitude of its charge.

A charged particle with a charge-to-mass ratio of \(|q| / m=5.7 \times\). \(10^{8} \mathrm{C} / \mathrm{kg}\) travels on a circular path that is perpendicular to a magnetic field whose magnitude is 0.72 T. How much time does it take for the particle to complete one revolution?

The drawing shows a parallel plate capacitor that is moving with a speed of \(32 \mathrm{m} / \mathrm{s}\) through a \(3.6-\mathrm{T}\) magnetic field. The velocity \(\overrightarrow{\mathbf{v}}\) is perpendicular to the magnetic field. The electric field within the capacitor has a value of \(170 \mathrm{N} / \mathrm{C},\) and each plate has an area of \(7.5 \times 10^{-4} \mathrm{m}^{2} .\) What is the magnetic force (magnitude and direction) exerted on the positive plate of the capacitor?

The two conducting rails in the drawing are tilted upward so they each make an angle of \(30.0^{\circ}\) with respect to the ground. The vertical magnetic field has a magnitude of \(0.050 \mathrm{T}\). The \(0.20-\mathrm{kg}\) aluminum rod (length \(=\) \(1.6 \mathrm{m}\) ) slides without friction down the rails at a constant velocity. How much current flows through the rod?

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