Share
Explore BrainMass

DC

Direct current is the unidirectional flow of electric charge. Direct current is produced by sources such as batteries, solar cells, commutator-type electric machines of the dynamo type. It can also flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or through a vacuum. The DC current flows in a constant direction appose to alternating current (AC). Historically, direction current was called galvanic current.

Direct current may be found from an alternating current supply by use of a current-switching arrangement. This arrangement is called a rectifier. A rectifier contains electronic elements or electromechanical elements that allows current to flow only in one direction. DC may also be obtained from AC with an inverter or a motor-generator set.

Direct current is used in nearly all electronic systems as the power supply. Very large quantities of direct current power are used in the production of aluminum and other electrochemical processes. DC is also used in some railway propulsion. High-voltage direct current is used to transmit large amounts of power from remote generation sites or to interconnect alternating current power grids.

Although DC stands for direction current, it also can refer to constant polarity. Under this definition, DC voltage can vary in time. This can be seen in the raw output of a rectifier or the fluctuating voice signal on a telephone line. Some forms of direct current have almost no variation in voltage, although, it may still have variations in output power and current.

Categories within DC

Electric Power

Postings: 57

Electric Power is the rate at which electric energy is transformed by an electric circuit.

Potential divider and its Thevenin's circuit.

(a) A potential divider is to supply a voltage of 10 V, constant to better than 10%, into a load which can draw current up to a maximum of 50 mA. Design a potential divider for a 40 V battery (internal resistance 1 ohm) that would guarantee these conditions. (b) Determine Thevenin's circuit for the circuit of (a)

eat generation and maximum thermal resistance of class A and B

The DC input power, heat generation and maximum thermal resistance of class A and B amplifiers are calculated. We know that the AC output power is 200 Watts, and that the Class A and Class B amplifiers operate with the maximum theoretical efficiency. We also know that the BJT power transistor has a maximum junction temperature

Determining the initial angular acceleration of a coil

A uniform rectangular coil of total mass 270 g and dimensions 0.5m x 1.0m is oriented perpendicular to a uniform 3.90-T magnetic field (the figure). A current of 2.30 A is suddenly started in the coil. Find the initial angular acceleration of the coil just after the current is started (rad/s^2). See document attached for

Electromagnetic Induction Lab

See attached lab report file. Please complete the graph for Step 9 under procedures (a graph of Primary Current vs. Galvanometer Deflection using the data from Steps 6 and 7) and provide results and conclusions. Please answer the four questions, the optional question and exercise.

Expression for the magnitude and direction of a magnetic field

Please show all the work. Problem #1: A closed section of a wire in the shape shown in bold in the figure (attached) carries a uniform current I counterclockwise. This section of wire lies completely in the plane of the paper. The figure consists of three-quarters of a circle of radius R and two straight lines, both of len

A Series RC circuit is analysed and questions answered

A circuit (SEE ATTACHMENT) consists of a switch, a series resistance of R = 50 Ohms, connected to a parallel arrangement of two capacitors of 6 uF and 3 uF. The supply voltage source is 10V DC PART A: Calculate the time constant of the circuit PART B: What is the current flowing through the resistor straight after the swit

Inductance of Solenoid

A solenoid of inductance L is connected, via a resistance R, to a battery of fixed voltage V0. If the current is denoted by I(t), the voltage across the solenoid will be VL(t) = LdI/dt . The switch is closed at t = 0. (a) Determine I(t) and VL(t). (b) What is the total energy delivered to the solenoid between t = 0 and t = 1

Physics - Resistance Problem

1. This pre-lab explores the characteristics of wires in DC circuits. Keep in mind that an ordinary wire has low but finite resistance. For these questions assume the wire resistance is 0.1 Ohms, the power supply is an ideal 6V voltage source, and the light bulb resistance is 30 Ohms. A. For the circuit below, one such wi

Comparing current from the battery

Please include all steps/reasoning. How does the current from the battery compare when the switch is open (and has been open for at least five minutes) and when the switch is closed (and has been closed for five minutes) in each of the circuits below? Explain. Please see attached file for full problem description.

D.C. Circuits: Resistances in Series, Parallel and Current

I need some help with these two problems: 9. Consider the shown below. If we make the nichronic wire longer, what happens to the: - (A) Equivalent resistance of the bulb (bulb B + wire) combination? - (B) Current through Bulb A? - (C) Voltage across Bulb B? - (D) Voltage across Bulb A? - (E) Current through Bulb B? In eac

Magnitude and Direction of Net Force on Loop

A long straight wire carries a current of 31 A to the right. Next to the wire is a square loop with sides 1.0 m in length, as shown in the figure below. The loop carries a current of 2.7 A in the direction indicated. Calculate the magnitude and direction of the net force acting on the loop.

Capacitors in Series Information

I have a question that I need a little help with. A 5.0 uf capacitor is connected to a 3.5 uf capacitor, and both of them are connected to a 6 volt battery. 1) what is the charge on each capacitor? What is the voltage on each capacitor? 2) With the battery still connected, the 3.5 uf cap is accidentally shorted out. As

Resistance problems measuring current in a circuit

See attached files. 1. Find the current in each resistor in attachment #1 which is #27 on the page and it is circled. 2. Find a). the equivalent resistance of the circuit in the second Attachment or #47 on page and it is circle as well, b). each current in the circuit, c). the potential difference across each resisto

Magnetism questions are featured.

1. A lovely way to shield against the Earth's magnetic field was used in a monopole experiment at Stanford University. A deflated lead-foil balloon is cooled below its critical temperature. Inflating the balloon then provides a field-free region inside of its hollow. How does it work? 2. A flat cirular coil having a diameter