Explore BrainMass


Electromagnetic Induction and induced EMF

Magnetic resonance imaging (MRI) is a medical technique for producing pictures of the interior of the body. The patient is placed within a strong magnetic field. One safety concern is what would happen to the positively and negatively charged particles in the body fluids if an equipment failure caused the magnetic field to be sh

output EMF of a generator

(See attached file for full problem description) 4. The drawing below shows a plot of the output emf of a generator as a function of time t. The coil of this device has a cross-secontal area per turn of 0.040 m2 and contains 136 turns. Find a. the frequency of the generator in Herz b. the angular speed in rad/s c. the magnit

Capacity, charge and voltage

The radii of curvature of the spheres of a spherical capacitor is given and to find the charge, charge density and work done when it is connected to a battery. See attached file for full problem description.

Inductance of a Solenoid

A long solenoid of length 8m with a cross-sectional area of 5.0x10^-5 m^2 contains 52,000 turns. 1) Find the self-inductance of the solenoid, assuming that the core is air. 2) If the current in the winding starts at 0 A and is increased steadily to 1.5 A in a time of 0.20 sec, what is the EMF induced in the solenoid?

Assorted Problem Set on Currents

See the attached file. 1. a) The magnitude of the earth's magnetic field at the surface of the earth is slightly less than one gauss.( I answered False and the answer was true) b) The torque exerted on a current loop by a uniform field tends to orient the plane of the loop perpendicular to the magnetic field.(I answered fals

RL Circuits: Growth and decay of current in inductor

See attached circuit. Note current source is 2A,Resistors are 2 Ohms, Inductor 2H. Assume that the switch has been open for a long time and that it closes at t=0 sec. The switch remains closed thereafter. How do I solve for Vx(t) and Ix(t)?

2 Problems

1. What is the definition of displacement current and how does it arise? Does displacement current have any real significance? Explain 2. Write down the maxwell's equations of electromagnetism, and state the laws they represent. Explain the meaning of all the symbols used.

Induction and Energy Transfer

A metal rod is forced to move constant velocity V along two parallel metal rails, connected with a strip of metal at one end. A magnetic field of magnitude B = .350T points out of the page. a) if the rails are separated by a 25.0 cm and the speed of the rod is 55.0 cm/s, what emf is generated? b) if the rod has a resista

Electromagnetic Induction: Induced EMF and Current

Two parallel loops of wire having the same common axis. The smaller loop of (raduis r ) and is above the larger loop (raduis R) by a distance X>>R. The magnetic field due to the counterclockwise current i in the larger loop is nearly uniform throughout the smaller loop. Suppose that x is increasing at a constant rate dx/dt = v.

DC Circuits: Time Varying Current and Voltages

Consider the circuit of Figure P4.18 in which the switch has been open for a long time prior to t=-0. Determine the values of vc(t) before t=0 and a long time after t=0. Also, determine the time constant after the switch closes and expressions for vc(t). Sketch vc(t) to scale versus time for -2 <= t <= 5. Consider the circuit

16 good questions on electromagnetism

(See attached file for full problem description with proper symbols and diagrams) --- 3.1 A long wire carries a current of 2 A along the +z axis. Calculate B in free space at (3,4,9). 3.2 Inside a long conductor of radius a, the magnetic field is H = 5 rho;/(2pi a2) a(phi) A/m. (a) Determine the current density J. (b) D

Changing magnetic field

Transcranial magnetic stimulation (TMS) is a noninvasive method for studying brain function, and possibly for treatment as well. In this technique, a conducting loop is held near a person's head. When the current in the loop is changed rapidly, the magnetic field it creates can change at a rate of {see attachment}. This rapidly

Faraday's Law of Electromagnetic Induction 2

A constant magnetic field passes through a single rectangular loop whose dimensions are 0.35 m x 0.55 m. The magnetic field has a magnitude of 2.1 T and is inclined at an angle of 70° with respect to the normal to the plane of the loop. (a) If the magnetic field decreases to zero in a time of 0.52 s, what is the magnitud

Phasor Diagram for Synchronous Generator

A 60-Hz 24-kV 250-MVA Y-Connected salient-pole synchronous generator (Xd=1.75 per unit, Xq=1.40 per unit) is operating with a phase-A to a neutral voltage of 14 cos wt kV and a phase-A current of 5.75 cos wt kA; the currents and voltages are balanced at three-phase. The rotor angle is known to be wt+37 degrees. a) Draw a pha

Light and Electricity

1. A proton of charge + 1.6 x 10^(-19) C and mass 1.67 x 10(-27)kg is introduced into a region of B = 1.5 T with an initial velocity of 1.25 x 10^6 m/s perpendicular to B. What is the radius of the proton's path? 2. A coil 17 cm in diameter and wound with 12 turns of wire is placed with the plane of the coil at right angles t


A 25-turn circular coil of wire has diameter 1.00 m. It is placed with its axis along the direction of the Earth's magnetic field of 50.0 &#956;T, and then in 0.200 s it is flipped 180°. An average emf of what magnitude is generated in the coil?

Magnetic field : key information

A 6.30cm diameter wire coil is initially oriented so that its plane is perpendicular to a magnetic field of 0.740T pointing up. During the course of 0.130s, the field is changed to one of 0.310 T pointing down. What is the average induced emf in the coil?

bar sliding in a magnetic field on rails - Voltage induced

Imagine that we have two metal rails 20 cm apart connected by a light bulb. The rails are placed in a 1.0 T magnetic field oriented vertically downward. We then constrain a bar to slide on the rails toward the lightbulb in this magnetic field. How fast do we have to move the bar to put a voltage difference of 3.0 V across the

current in a 48.1 mH inductor changes with time

The current in a 48.1 mH inductor changes with time as I = bt^2 - at. With a = 2.7 A/s and b = 3 A/s^2, find the magnitude of the induced emf at t = .992 s. Units of V At what time is the emf zero? Units of s

conducting wire, magnetic flux, induced EMF, resistance, current

See attached file. In the figure, ABCD is a conducting wire. A conducting bar EF is laid on top of the wire and slid toward BC with a speed of .030 m/sec. A constant magnetic field B of 2.0*10^(-5)Tesla points out of the paper. The length of BC is 1.5m and the distance of the bar from EF is initially 2.0m. 1) What is the i

Batteries and Circuits

PART ONE: A battery that supplies an emf of 6.0 V has an internal resistance of 0.20 ohm. It is connected to a load resistor of 8.8 ohms. The total Current in the entire circuit is: A) less than 0.25 A B) between 0.25 A and 0.50 A C) between 0.50 A and 1.0 A D) greater than 1.0 A PART TWO: A battery of fou

Calculate the self-inductance of the coil and the emf induced in it.

A coil of 500 turns is wound on a wooden ring having a mean diameter of 8 cm and a cross sectional area of 1.5 cm^2. Assuming relative permeability of wood is 1, calculate the self-inductance of the coil and the emf induced in it when the direction of a DC current of 5A flowing in it is reversed in 0.2 sec?