A 120-V, series-wound dc motor draws 0.50 A from its power source when operating at full speed, and it draws 2.0 A when it starts. The resistance of the armature coils is 10 Ω . (a) What is the resistance of the field coils? (b) What is the back emf of the motor when it is running at full speed? (c) The motor operates at a different speed and draws 1.0 A from the source. What is the back emf in this case?

Q: A 0.260 m radius, 570–turn coil is rotated one–fourth of a revolution in 4.73 ms, originally having…

A: Given data: Number of turns in the coil, n =570 turns Radius, r =0.26m time,∆t =4.73 m s=4.73×10-3s…

Q: A ring rotates around the Y-axis in a magnetic field B=b0sinwt ax Wb/m2. The voltage induced in the…

A: when ring rotates then the flux through ring vary which can cause the flux to change due to which an…

Q: A 0.30-m-long metal bar is pulled to the left at constant speed of 20 m/s perpendicular to a…

A: The induced emf is determined by the rate of flux change Emf=dϕdt=ddtBxl=Bldxdt=Blv

Q: The conducting bar in the figure below is 0.1 m long and moves to the right with a speed of 10 m/s…

A: Length (L) = 0.1 m speed (v) = 10 msMagnetic field strength (B) = 1.5 T

Q: Suppose that a rectangular toroid has 2000 windings and a self-inductance of 0.040 H. If h = 0.10 m…

A: Using the energy stored in an inductor, U=12LI2I=2UL

Q: A square coil of wire of side 2.25 cm is placed in a uniform magnetic field of magnitude 2.00 T…

A: Here length of square = 2.25 cmUniform magnetic field = 2TTurns of the coil (N) = 27.5Resistance (R)…

Q: A long, straight solenoid with a radius of rs = 3.0 cm and a length of y = 25 cm is wound with 1,500…

A:

Q: A long, straight solenoid with a radius of rs = 3.0 cm and a length of y = 25 cm is wound with 1,500…

A:

Q: A generator has a 0.054 T magnetic field and a coil with  51 turns each with an area of 0.218 m2..…

A: Given: The strength of the magnetic field is 0.054 T. The number of turns is 51. The area of the…

Q: Below is a Motional EMF problem with a sliding, conducting bar connecting a wire loop within a…

A: Given:- The velocity of the bar V = 25.0 m/s  The magnetic field B = 0.640 T  The resistance in the…

Q: In which of the given cases, the induced current in the loop will not be obtained A. The loop and…

A: According to Faraday's law, an Emf is produced across a conductor when the magnetic flux is…

Q: How fast (in rad/s) must a 92-turn coil spin in a 0.039 T field to create a peak voltage of 8.3 V?…

A: Given number of turns = N = 92 strength of magnetic field = B = 0.039 T peak voltage = Vmax = 8.3 V…

Q: A 20.9 turn conductive loop encloses an area of 0.57 m2. At what constant rate should the magnetic…

A: Given:-             A 20.9 turn conductive loop encloses an area = 0.57 m2.…

Q: An emf of 17.0 mV is induced in a 480-turn coil when the current is changing at the rate of 10.0…

A: The self induced emf in a RL circuit is defined as ε=L∆I∆t or we ca write  L=ε∆I∆t In this question,…

Q: A magnet is placed into a coil. The induced emf across the coil is 10 mV. What would the emf be if…

A: The expression for the induced emf in the coil is      ε=NBAω Here N is number of turns, B is the…

Q: A uniform magnetic field points into the page. The square current loop shown is rotated in this…

A:

Q: motor has coils with a resistance of 42.0 Ω and operates from a voltage of 240 V. When the motor is…

A: The back emf is represented as a variable emf that opposes the one driving the motor. Back emf is…

Q: Which of the following will not increase a generator’s voltage output?(a) Rotating the generator…

A: When the Magnetic Field is rotated in a manner, that it becomes parallel to the axis of the…

Q: .A 110 V direct current motor generates a back-emf of 98 V when it runs at full speed. If the…

A: Given Data: Applied voltage, V=110 V Back-emf, ε=98 V Resistance, R=10 Ω ⇒Motor runs at full speed.

Q: The bolt of lightning depicted in the figure passes 200 m from a 90 turn coil oriented as shown. If…

A:

Q: A 100-tum square coil of side 20.0 cm rotates about a vertical axis at 1.8 x10 rev/min as indicated…

A: Given, Number of turns N = 100 Side of coil L = 20 cm = 0.2 m Angular speed = 1.8 x 103 rev/ min =…

Q: A 100-turn square coil of side 20.0 cm rotates about a vertical axis at 4.9 x103 rad/min as…

A: Faraday's law of induction states that an emf is induced in a coil when there is a change in the…

Q: A 230 V shunt motor takes a total current of 35 A. If the field winding resistance is 65Ω and the…

A:

Q: A 105-turn square wire coil of area 0.040 m2 rotates about a vertical axis at 1,800 rev/min, as…

A: Emf induced in the coil ε=dϕdt=ddtNBAcosθ=NBAωsinθ            ω=dθdtεmax=NBAω            sinθmax=1

Q: 10 and 11 please

A: 10. When an emf is produced in a coil because of the change in current in a coupled coil, this…

Q: When the current in a toroidal solenoid is changing at a rate of 0.03A/s, the magnitude of the…

A: Given data Current changing at a rate of 0.03 A/s Magnitude of induced emf  11.9 mV Current 1.34 A…

Q: Two coils are placed near each other and they have a mutual inductance of 887.4 mH. If the current…

A:

Q: A long, straight solenoid with a radius of rs = 3.0 cm and a length of y = 25 cm is wound with 1,500…

A:

Q: For the following DC motor, in what direction will the loop spin? The loop will spin…

A:

Q: A coil with a self-inductance of 6.0 H is connected to a dc battery through a switch. As šooh as the…

A:

Q: Determine the induced emf in the alternator as a function of time. (Assume is in V.) = (b)…

A:

Q: A 100-turn square coil of side 20.0 cm rotates about a vertical axis at 1.6 x10 rev/min as indicated…

A: Data Given ,  No. Of turns ( N ) = 100 Side of the coil ( l ) = 20 cm = 0.2 m So , area of the coil…

Q: A 100-turn square coil of side 20.0 cm rotates about a vertical axis at 5.9 ×10 rad/min as indicated…

A: (given) Number of turns in the coil = 100               Side of square coil = 20 cm…

Q: A 40-turn coil has a diameter of 13 cm. The coil is placed in a spatially uniform magnetic field of…

A:

Q: A 9.00 - V battery is connected to a coil which has a self-inductance of 125 mH and a resistance of…

A: The amount of energy stored in the coil is E=12LI2=12125×10-3 H0.500 A2=0.015625 J

Q: An emf of 24.0 mV is induced in a 500-turn coil when the current is changing at a rate of 10.0 A/s.…

A:

Q: What is the induced emf in the below coil if it is moving upward at 4.2 m/s in a uniform magnetic…

A:

Q: loop is placed in a region where the magnetic field is changing. At t = 0 s the magnetic field is 1…

A: A loop is placed in a region where the magnetic field is changing. At t = 0 s the magnetic field is…

Q: A long, straight solenoid with a radius of rs = 3.0 cm and a length of y = 25 cm is wound with 1,500…

A:

Q: At a certain instant the current flowing through a 5.0-H inductor is 3.0 A. If the energy in the…

A: Given data: Current I=3.0A Inductance L=5.0H Change in Energy dE/dt=3.0J/s

Q: A 100-turn square coil of side 20.0 cm rotates about a vertical axis at 4.8 ×103 rev/min as…

A:

Q: An emf is induced by rotating a 1070 turn, 20.0 cm diameter coil in the Earth's 4.95 ✕ 10−5 T…

A:

Electromagnets

The word "electromagnet" is composed of two words, ‘electro’ and ‘magnet’. It is a type of magnet in which an electric current helps in the generation of a magnetic field. Electromagnets usually consist of two major parts, wire and a coil around which the wire is wound. This is called a solenoid. When an electric current is allowed to pass through the coiled wire, the electric current produces a magnetic field. This magnetic field is present only when current is passing through the wire.