Electric machinery fundamentals
5th Edition
ISBN: 9780073529547
Author: Chapman, Stephen J.
Publisher: MCGRAW-HILL HIGHER EDUCATION
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Textbook Question
Chapter 1, Problem 1.3P
A force of 10 N is applied to a cylinder of radius
What are the magnitude and direction of the torque produced on the cylinder? What is the angular acceleration of the cylinder?
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The metal sphere in figure hangs by a thread. When the north pole of a magnet
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is reversed and its south pole is brought near the sphere. How does the sphere
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Problem 1
In the magnetic circuit shown in figure P-1 the depth of the core is 5 cm. The winding has
400 turns and the relative permeability of the core is 4000. Determine the flux produced
in the core for a current in the coil of 5 A.
10cm
N
20cm →→
Figure P-1
10cm
T
10cm
20cm
10cm
A wire loop that is carrying a current I is shown in the figure. The direction of the current is also indicated in the
figure. This loop is inside a magnetic field whose flux density is given as
B = -5x + y
The forces acting on this loop will try to
◆ axis (Note: Be careful about the sign of the axis as it will indicate the rotation direction).
◆
it. And the net torque on the loop will try to rotate it along the
I
N
X
Chapter 1 Solutions
Electric machinery fundamentals
Ch. 1 - What is torque? What role does torque play in the...Ch. 1 - What is Amperes law?Ch. 1 - What is magnetizing intensity? What is magnetic...Ch. 1 - How does the magnetic circuit concept aid in the...Ch. 1 - What is reluctance?Ch. 1 - What is a ferromagnetic material? Why is the...Ch. 1 - How does the relative permeability of a...Ch. 1 - Prob. 1.8QCh. 1 - What are eddy current losses? What can be done to...Ch. 1 - Why are all cores exposed to ac flux variations...
Ch. 1 - What is Faraday law?Ch. 1 - What conditions are necessary for a magnetic field...Ch. 1 - What conditions are necessary for a magnetic field...Ch. 1 - Prob. 1.14QCh. 1 - The linear machine in Figure 1-19 is running at...Ch. 1 - Just how does a decrease in flux produce an...Ch. 1 - Will current be leading or lagging voltage in an...Ch. 1 - What are real, reactive, and apparent power? What...Ch. 1 - What is power factor?Ch. 1 - Prob. 1.1PCh. 1 - A flywheel with a moment of inertia of 4kgm2 is...Ch. 1 - A force of 10 N is applied to a cylinder of radius...Ch. 1 - A motor is supplying 50Nm of torque to its load....Ch. 1 - A ferromagnetic core is shown in Figure P1-2. The...Ch. 1 - A ferromagnetic core with a relative permeability...Ch. 1 - A two-legged core is shown in Figure P1-4. The...Ch. 1 - A core with three legs is shown in Figure P1-5....Ch. 1 - A two-legged core is shown in Figure P1-4. The...Ch. 1 - A wire is shown in Figure P1-7 that is moving in...Ch. 1 - Repeat Problem 1-10 for the wire in Figure P1-8.Ch. 1 - Prob. 1.12PCh. 1 - A core with three legs is shown in Figure P1-10....Ch. 1 - A two-legged magnetic core with an air gap is...Ch. 1 - A transformer core with an effective mean path...Ch. 1 - The core shown in Figure P1-2 has the flux shown...Ch. 1 - Prob. 1.17PCh. 1 - Prob. 1.18PCh. 1 - Prob. 1.19PCh. 1 - Demonstrate that Equation (1-59) can be derived...Ch. 1 - Prob. 1.21PCh. 1 - Prob. 1.22PCh. 1 - For the linear machine of Problem 1-22: When this...
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- A dc generator consists of 100 wires connected in series and lying in a radius of 10 cm. the effective length of each conductor is 15 cm. The radial field has a strength of 0.8 T. If the armature rotates at 1,200 rpm, solve the voltage generated. Draw the diagram. Thanksarrow_forwardA ring having a cross-sectional area of 500 mm?, a circumference of 400 mm and D=800microWb has a coil of 200 turns wound around it. Relative permeability of ring is 380. Calculate the magnetomotive force. o a. 1432A. o b. 1344AT O c. 1342AT o d. 1442Atarrow_forwardThe negative field intensity required to force the residual magnetism is known as. O Magnetic field density O Coercive force O Magnetomotive force None of optionarrow_forward
- As shown in the figure, a DC motor is driven by a voltage source Vs through a resistor R = 2 N. The rotor of the motor comprises five wire turns with dimensions of x = 60 cm and y = 30 cm. The magnetic flux density B exerted on the rotor is assumed to be constant at 40 mT with a uniform direction, as marked in the figure. Although the torque that B imposes on the rotor varies with the angle 0 between the rotor and B, for simplicity, a constant equivalent torque is considered which is assumed to be 64% of the peak torque value. This equivalent torque balances the mechanical load torque, giving a constant speed n of the rotor. In the beginning, I = 5 A and n = 2000 rpm. The energy-conversion efficiency of the motor is 70%. After running for some time, the mechanical load torque increases by 10%. What would the value of n be after the increase of the load? Assume that the voltage across the motor is VM = kw, where k, is a constant. Choose the value that is closest to the answer. B S + VM…arrow_forwardAn electromagnet is used to support a solid piece of steel, as shown in the figure below. A force of 10,000 N is required to support the weight at a distance of x=0.5m. The cross-sectional area of the magnetic core (the fixed part) is 0.01m2. The coil has 1,000 turns. Assume negligible reluctance in steel and negligible fringing in the air gaps. Fixed fe Movable Determine: 1. The current required to lift the weight | 2. The minimum current required to keep the weight from falling for x = 1.0 mm. Assume negligible reluctance in steel and negligible fringing in the air gaps. Assumptions: Negligible reluctance for the steel parts and negligible fringing in the air gaps.arrow_forwardCalculate the magnetic induction in air at a point 5 cm from a long straigh wire carrying a current of 15 A. As shown in the figure below, two long parallel wires are 10 cm apart in a and carry currents of 6.0 A and 4.0 A. C D 10 cm 6.0 A 4.0 A Show that the force per unit length on wire C can be expressed as 24.0 Ho 0.20 aarrow_forward
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