# how to find direction of torque in magnetic field

Using Eq. Step 1: Read the problem. Solenoids have many practical implications and they are mainly used to create magnetic fields or as electromagnets. In atomic physics, the magnetic quantum number (m l) is one of the four quantum numbers (the other three being the principal, azimuthal, and spin) which describe the unique quantum state of an electron.The magnetic quantum number distinguishes the orbitals available within a subshell, and is used to calculate the azimuthal component of the orientation of orbital in space. Your fingers point in the direction of , and your thumb needs to point in the direction of the force, to the left. When it's antiparallel, Students begin to focus on the torque associated with a current carrying loop in a magnetic field. b. From (38.5.2) we can deduce unit of Magnetic force does no work on a moving charge Magnetic torque on a current loop does work: W= There is no net force, only torque, on a current loop (=magnetic dipole moment) in B. The magnitude of magnetic force on each length is F 1 = I lB F 1 = I l B, so substituting this value in above equation gives. As shown in Fig. So, forces on the wires RS and PQ will be: The force acting on the North Pole is along with the magnetic field. Both the direction and magnitude of the torque can be programmed by specially designing the magnetic plate magnetization and manipulating the applied magnetic field. B First, consider rotating to position c. What are the signs of the work done by you and the work done by the field? Step 2: Use the Right-Hand rule to We want to rotate the dipole in the CCW direction. My textbook states That the torque experienced by a current carrying loop due to a magnetic field B , is given by the equation = M B ,where M denotes the magnetic moment of the current loop= I A . = 0, sin0 = 0, = 0. A large number of such loops allow you combine magnetic fields of each loop to create a greater (N-m) Solution: Magnetic field (B) direction is shown. If the external magnetic field is uniform, then there is no force on the dipole. Step 2: Identify the direction of the Electric Field. When a current is placed on a magnetic field, the direction of the magnetic force acting on such current is determined using the We have step-by-step solutions for your textbooks written by Bartleby experts!

The magnetic dipole moment of a loop of wire carrying a current in a magnetic field is defined as the torque acting on the loop of wire divided by the magnetic field strength: = . The direction of the torque is perpendicular to the direction of the area of the loop as well as the direction of the magnetic field i.e., along . When the magnet lies perpendicular to the direction of the magnetic field. Figure 11.6. In the case of static charges, the total magnetic force is zero. For part a, since the current and magnetic field are perpendicular in this problem, we can simplify the formula to give us the magnitude and find the direction through the RHR-1. Where does this work come from? Hence, it shows that a bar magnet and a solenoid produce similar magnetic fields. i.e. By convention, magnetic field lines leave the north pole and enters the south pole of a magnet. The direction of rotation of these motors can be easily changed.

(A) A diagram of the ST-FMR measurements, illustrating the magnetization precession driven by the spin torque, including the damping-like torque DL and/or field-like torque FL. (iv)When the bar magnet is perpendicular to the direction of applied magnetic field, then the moment of couple is maximum. For a bar magnet, the magnetic dipole moment is directed from the south pole of When current is passed through the loops, the magnetic field exerts torque on the loops, which rotates a shaft. The force is acting inwards. The resultant force is thus perpendicular to the direction of the velocity and the magnetic field, the direction of the magnetic field is predicted by the right-hand thumb rule. This is the magnetism that is responsible for diamagnetism. Magnetic force does no work on a moving charge Magnetic torque on a current loop does work: W= There is no net force, only torque, on a current loop (=magnetic dipole moment) in B. The direction of the force may be found by a righthand rule similar to Let radius of solenoid be a. Three different orientations of a magnetic dipole moment in a constant magnetic field are shown below. Magnetic-field dependence of the relative length change L/L of TaAs (sample 2) is measured along the [100] direction at 25 mK for various angles between the direction of B and the a axis. Magnetic field due to a long current carrying solenoid. For the rectangular wire, we can substitute the expression for torque we calculated previously: = = . A wire has a length of and is used to make a circular coil of one turn. Example: Find the magnetic field produced by the solenoid if the number of loop is 400 and current passing through on it is 5 A. The relative permeability of magnetic iron is around 200 The inductor head is composed of a single-turn copper coil and a magnetic field Computing the spatial derivative of the magnetic field or magnetic flux density is useful in areas such as radiology, magnetophoresis, particle accelerators, and geophysics . So, forces on the wires RS and PQ will be: A uniform magnetic field pointing in the +y direction is applied. A magnetic field exerts a torque which tries to align the normal vector of a loop of current with the magnetic field. The size of the torque on a loop of current is torque = (# turns) * (current) * (loop area) * (mag field) * sin(theta) where theta is the angle between the magnetic field and Find the current through a loop needed to create a maximum torque of 9.00 N. The loop has 50 square turns that are 15.0 cm on a side and is in a uniform 0.800-T magnetic field. The black arrow denotes the direction of I RF with a current density J C. The red and blue arrows indicate spin polarizations and magnon current J M, respectively. Torque = F x d. On this page we give a simple derivation of the force and torque on a small magnetic dipole which is in a non-uniform magnetic field. = 90, sin90 = 1, = mB. And the wires RS and PQ are still perpendicular to the magnetic field while QR and SP are making an angle with the magnetic field. Where m- magnetic moment and B- magnetic field are applied. The magnet rotates in a clockwise direction because it forms a parallel couple. Find (a) The direction and (b) magnitude of the electric current to levitate the copper rods gravitation force. Textbook solution for Fundamentals of Physics Extended 10th Edition David Halliday Chapter 29 Problem 10P. The model may differ a little from a real solenoid, but the agreement between the two is quite good. This is accomplished by reversing the connections of two of the power lines to the motor leads. Also, the direction of the magnetic field lines in Thus, when is 90 (means magnet is perpendicular to the direction of the magnetic field) magnetic Torque is maximum. If the perpendicular to the coil is at an angle to the field direction, then the torque exerted on the coil is Fd where d = a sin q. Solution: 2. Conclusion. When a current loop is said to be placed in a magnetic field, it is believed that the loop tends to orient according to the field direction due to the influence of that field. where is the angle between the dipole and the field. The direction of the magnetic field can be determined using the "right hand rule", by pointing the thumb of your right hand in the direction of the current. Horizontal sides: the forces cancel but they generate a torque. The torque vector points in the plane of the thumb if a hand is wrapped around the plane of rotation with the fingers oriented in the force vector. Fingers wrap wire in direction of the circular B-field. ab is the area of the loop, so the torque is, in this case, = IAB. They are placed inside the magnetic field. =NIABsin = NIAB si is the formula that is used to find which way the torque is facing. The period of the alpha-particle going around the circle is In this situation they will get adjusted along north south direction. Download scientific diagram | The magnetic torque on a Janus microdimer without a wall during one period under the condition of an external magnetic field The coil rotates along its own axis due to this torque. Case 2: Here, the angle between the vectors M and B = . The direction of the magnetic moment is perpendicular to the current loop in the right-hand-rule direction, the direction of the normal to the loop in the illustration. Considering torque as a vector quantity, this can be written as the vector product. We have been slightly glib in discussing the mechanical torque. Considering the current loop as a tiny magnet, this vector corresponds to the direction from the south to the north pole. (b) Torque in the y-direction. Definition: The magnitude of the magnetic dipole moment of a magnet (or current-carrying coil) is defined as the magnitude of the torque that acts on it when it is placed with its axis at right-angles to a uniform magnetic field of unit induction. current I, with an angle between the area vector and the magnetic field , is:. Since this torque acts perpendicular to the magnetic moment, then it can cause the magnetic moment to precess around the magnetic field at a characteristic frequency called the Larmor frequency. The position where the magnetic moment is opposite to the magnetic field is said to have a higher magnetic potential energy. Let B point in the z direction. 1 shows a rectangular loop of wire that carries a current I and has sides of lengths a and b. Calculating the Direction of a Magnetic Force on a Moving Charge in a Magnetic Field. where is the angle between the dipole and the field. Sloping sides: the forces cancel. If we place a magnetic needle in a magnetic field, the needle deflects. F = I l B . Example 22-4 Magnetic Levity A copper rod 0.150m long and with a mass 0.0500kg is suspended from two thin wire. The normal clockwise direction of the motor that the rotor is powering can be manipulated by using the magnets and magnetic fields installed in the design of the rotor, allowing the motor to run in reverse or counterclockwise. a. magnetic field. Share 1 . P Figure 19.1. direction of magnetic field at point P. FAQ on Magnetic Field and Work Magnetic force does no work. The magnetic dipole moment md is the torque acting on a coil carrying electric current and its plane is parallel to a magnetic flux density of 1 T. The measuring unit of the magnetic dipole moment is (N.m/T) (Newton.meter/Tesla) which is equivalent to Ampere.m (A.m). Top views of a current-carrying loop in a magnetic field. 1). Obviously, this value is not constant over the spacecrafts body, but with a first order approximation it can be assumed to be constant and equal to 0.6. 11.5 Force and Torque on a Current Loop; 11.6 The Hall Effect; 11.7 Applications of Magnetic We can use the Biot-Savart law to find the magnetic field due to a current. The loop is in a uniform magnetic field: B = B j ^. (a) The equation for torque is derived using this view. For the rectangular wire, we can substitute the expression for torque we calculated previously: = = . Answer (1 of 2): If you want direction of magnetic moment of a magnetic needle or bar magnet then arrange them such that they can rotate freely in horizontal plane. This is ~= IA~, where Iis the current and the magnitude of A~is the area Aenclosed by the loop. Therefore, we can define the magnetic moment of the current loop as, m = IA. When free to rotate, dipoles align themselves so that their moments point predominantly in the direction of the external magnetic field. But an electric motor (=a current loop in B) does work. This physics video tutorial focuses on topics related to magnetism such as magnetic fields & force. [Find the maximum torque on a 100-turn square loop of a wire of 10.0 cm on a side that carries 15.0 A of current in a 2.00-T field.] Electrical energy is converted into mechanical work in the procedure. A current-carrying coil kept in a magnetic field experiences a torque, which is the cross product of the magnetic moment and the field vector. Besides, the direction of the magnetic field can be determined using the right-hand rule by pointing the thumb of your right hand in the direction of the current. which means the dipole will rotate counterclockwise : still, the direction it needs to go to align itself with the field. The magnetic torque, , experienced by a single particle of volume V and domain magnetization M d whose moment is oriented at angle to applied induction B is given by =mHsin where m=M d V is the magnetic moment of the particle. The coil carries 2 amperes of current while in a magnetic field having a magnitude of 10 T. Determine the maximum torque. Three-phase motors turn in the direction of the rotating magnetic field. how to find direction of torque; The right-hand grasp rule is used to determine the path of the torque vector. In simplistic terms, the d axis is the main flux direction, while the q axis is the main torque producing direction.

Applying Flemings right-hand rule, the magnetic field is in a direction perpendicular to that of current. direction of torque on a current loop will be the same as the direction of cross-product of area vector and external magnetic field. rule: Grasp wire with right hand; point thumb in direction of I. Hi, The magnetic moment of a magnet is a quantity that determines the force the magnet can exert on electric current and the torque that a magnetic field will exert on it. Therefore the torque C is given by: Torque (C) on the coil = Fa sin = BNIba sin or: Torque (C) on the coil = BANI sin Calculating B-field for Long Wire. A long cylindrical coil having large number of turns is known as solenoid. Magnetic permeability: In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself. Where does this work come from?

Because the dipole in the magnetic field point in opposite directions, = B = = 0. They solve example problems as a class and use diagrams to visualize the vector product. HOW to find direction of magnetic moment . So torque=bFcos () Which is: = BIwbcos () Give a more general expression for the magnitude of the torque . Rewrite the answer found in Part A in terms of the magnitude of the magnetic dipole moment of the current loop .