Explore BrainMass

Ohm's Law

Ohm’s law states that the current through a conductor between two point is proportional to the potential difference across the points. This principle introduces the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship.

I = V/R


I is the current

V is the potential different across the conductor

R is the resistance

Ohm’s law states that the R is this relation with constant independence of the current.

In physics, the term Ohm’s law is also used to refer to various generalizations of the law originally formulated by Ohm.

J = σE


J is the current density

E is the electric field

σ is the conductivity

Calculating the Resistance of the Resistor

The resistance of a resistor is to be determined by measuring the voltage drop across it when passing a given current, as shown in the figure in the attachment. The instrument indications are 2 mA and 12.0 V, the ammeter having a resistance of 10 Ω and the voltmeter a resistance of 10kΩ. Calculate: (a) the resistance of

Ammeter-Voltmeter Method

The resistance of a coil is measured by the ammeter-voltmeter method. With the voltmeter connected across the coil, the readings on the ammeter and voltmeter are 0.4A and 3.2 V respectively. The resistance of the voltmeter is 500 Ohm. Calculate (a) the true value of the resistance and (b) the percentage error in the value of the

Norton and Thevenin Equivalent

Please see attached. Given the one-port network. The output port of the one-port is defined by terminals A and B. a) Find the Thevenin and Norton Equivalent circuits. b) Plot the current voltage characteristic of the one-port.

Electric Circuits: Loop Analysis

Please see attached problem and solve all parts using Loop Analysis only. Find all the currents in the circuit. Indicate all the voltage polarities and current directions.

resistance of telephone line

A circuit consists of a 48 volt battery at a telephone company central office which is connected to a twisted pair telephone line. At the other end of the line is a telephone handset with a resistance of 1000 ohms. The twisted pair has a loop resistance of 100 ohms per kilometer. (Loop resistance is the combined resistance

Physics: Electric Circuit Questions

See attached file. In the circuit shown in the attachment E=60V, R_1=40 Ohms, R_2=25 Ohms and L=0.3H. Switch S is closed at t=0 s. Just after the switch is closed a) What is the potential difference across the resistor R_1? b) Which point (a or b) is at higher potential? c) Find potential difference across the inductor (

Directly and Inversely Proportional

Hello, I cannot figure this out. Please help. Directly and Inversely Proportional A well known physical law describing the relationship between electrical current, voltage and resistance in a circuit is called Ohm's law, which can be paraphrased as follows: The current in a circuit is directly proportional to the vo

Trans-impedance Amplifier

(a) The circuit of FIGURE 2 (attached) is known as a trans-impedance circuit used for the measurement of very small currents. Derive the relationship between the output voltage V and the input current I; i.e. if V = kI find k in terms of R1, R2 and Rf. (b) Calculate the current I if Rf =10 mOhm (milli-Ohms), R1 = 90 kOhm, R2=

Analysis of Reflections on a Transmission Line

A transmission line of length l, characteristic impedance Z0 = 100 Ohm, and one-way time of flight T = l/c is connected at z=0 to a 100 volt DC battery through a series source resistance Rs = 100 Ohm and a switch. The z=l end is loaded by a 300 Ohm resistor. a) The switch at the z=0 end has been closed for a very long time so

Electricity Topics: Fields, Resistance, Series and Parallel

Q1(a) Define Electric current and quote its units as defined by SI quantities Q1(b) In a device if N = 5.4 x 10^6 electrons pass in a time of t = 40 ms determine the current that this equates to Q2(a) A calculator uses 50 uA of current in 300 ms with an applied voltage from a battery of 3.5V Calculate the number of el

Physics Circuits: charging time, voltage, current flow, discharge

Please see the attached problem. Consider the following transient RC-circuit and answer these questions in the given order. 1) Find charging the constant. 2) Find full-charged time. 3) Find charging equations. 4) Find voltage across and current flow for capacitor at t = 4 second/charging. 5) Find discharging ti

C++ program calculating current through a set of resistors

Writing a Program using Input and Output Arrays Procedure: 1. You will write one C program. Name it as YOUR LAST NAME_Lab07.cpp 2. Lab07 will be used to calculate the current that flow through five separate resistors based on a user's input of voltage (using Ohm's Law). It will use two "input arrays" and produce one "

Thermal Coefficient of Resistance

A 1.70 m cylindrical rod of diameter 0.450 cm is connected to a power supply that maintains a constant potential difference of 15.0 V across its ends, while an ammeter measures the current through it. You observe that at room temperature (20.0 degree Celsius ) the ammeter reads 18.7A , while at 92.0 degree Celsius it reads 1

Reducing power losses in transmission of alternating currents.

I know V=IR, P=IV, P=I^2R and P lost = I^2R. Here problem....Told like in an AC distribution system like a power grid when voltage increased current is decreased where R is constant over the power lines. If current were increased voltage would decrease. These equations above plotted numbers to prove , which is what is really

Series RL Circuit

The problem is in the right column of the attached page. There are two # 11's so it is the one on the right. See attached file for full problem description. You have a 200 ohms resistor, a 0.400 H inductor, and a 6.00 uF capacitor. Suppose you take the resistor and inductor and make a series circuit with a voltage source th

Resistance Between Electrodes

A square film of Nichrome, an alloy of nickel and chromium, has copper electrodes deposited on two opposite edges. Show that the resistance between the electrodes depends only on the thickness of the film on its conductivity, as long as the film is square. This surface resistance is expressed in ohms per square.

Modeling with first order Differential Equations (Five Problems).

9. When a vertical beam of light passes through a transparent medium, the rate at which its intensity I decreases is proportional to I(t). where t represents the thickness of the medium (in feet). In clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity Jo of the incident beam. What is the intens

Voltage Divider Circuit

The voltage divider network of Figure 2.37 (attached file) is expected to provide 5 V at the output. The resistors, however, may not be exactly the same; that is, their tolerances are such that the resistances may not be exactly 5 kΩ. a) If the resistors have ± 10 percent tolerance, find the worst-case output voltages.

Application of Faraday's law of electromagnetic induction

(See attached file for full problem description with proper symbols and diagrams) --- 1. How fast would you have to move a 1.0 m long conductor to produce a motional emf of 1.0 V in a 4 x 10^ -4 T magnetic field (assume that the conductor moves perpendicular to the field)? If a resistance of 0.5 ohm is co

Current in Resistor - which terminal will be positive?

Refer to attached picture). There is a current of 10.0 amperes initially in the long straight wire shown at the bottom of the following diagram produces a flux of 0.0511 webers in the single loop circuit containing the resistor. If the current in the long straight wire is uniformly reduced to ¼ of its original value in 1.99

Calculating maximum voltage, current and energy

Please help with the following problem. Step by step calculations are given. An L-C circuit consists of a 60.0 mH inductor and 250 µF capacitor. The initial Charge in the capacitor is 6.00 µC and initial current in the inductor is zero. a) What is the maximum voltage across the capacitor? b) What is the maximum current

Working with inductors - but connected to a battery

1. An inductor is connected to the terminals of a battery that has an emf of 12.0V and negligible internal resistance. The current is 4.86mA at 0.725 ms after the connections is completed. After a long time the current is 6.45 mA. What is a) The resistance R of the inductor? b) The inductance L of the inductor?

Electric Circuits

1) For the circuit below find: a) The current through R1. b) The current through R2. c) The current at the ammeter. See attached file for full problem description.

Transfer Function

Find the transfer function IL/Vs for the following circuit in the attached file.