Circuits III

Connecting Potential and Current
A battery is a source of _______ _______. The current that flows through a wire connecting the battery terminals is a consequence of the ______ _______. Because the ends of the wire are connected to the terminals of the battery: 
ΔV_wire = ______
The potential difference causes a current in the direction of _______ potential

Experiments show that there are two factors that determine the current (name them)
The current is ______ ______ to the potential difference. 
Adding a second battery ______ the potential difference, which ______ the electric field and, as a result, ______ the current

Define a quantity called the resistance R that relates to the properties of the wire. 
A ______ resistance implies that it is hard to move charges through the wire. The current depends on the ______ of the wire and the ______ ______ between the ends of the wire:
I = ______

The resistance of a wire depends on its _______ and the _______ of its materials. 
Resistivity is a property of the ______, it does not depend on the ______ and ______ of the material
Resistance characterizes a specific piece of the _______ having a specific _______. Short, thick wires have _______ currents and long, thin wires have ______ currents. A copper wire carries a ______ current than an iron wire of the same dimensions

State the formula for Resistance and explain its components. State the units

Resistivity, ρ characterizes the _______ properties of materials
An ideal (perfect) conductor would have ______ resistivity
An ideal insulator would have _______ resistivity
The resistivity of a metal ________ with increasing temperature
The inverse of the resistivity is the _______. (state the formula)

Different tissues in the body have different resistivities. Fat has a _______ resistivity than muscle, and so a higher resistance in the body indicates a higher portion of _____. Electrical impedance tomography passes a ______ ______ through a patient's torso to measure the resistance of intervening tissue

An image of a patient's torso generated from the resistance between many pairs of electrodes shows _______ resistance in red and _______ resistance in blue. 
Blood is a better _______ than tissue of the heart and lungs, so the motion of blood _______ the patient's resistance of the heart and ________ that of the lungs.
In a patient with circulatory problems, any deviation from normal blood flow would lead to _______ patterns of resistance in this image

State Ohm's Law and the formula it yields for current
Ohm's Law is NOT a fundamental law of nature: 
☞It is limited to those materials whose resistance R ______ ______ during use
☞Materials that obey Ohm's Law are said to be ______

The current through an ohmic material is _____ ______ to the potential difference.

Non-ohmic materials are those whose resistance changes with ______ or ______.
☞The current-voltage relationship is ______
☞State three important examples:

Define Resistors
There are a few basic types that will be very important as we start to look at electric circuits in detail, name them

Heating Elements
As charges move through a resistive wire, their electric energy is transformed into ______ energy, heating the _____. _____ in a toaster, a stove burner, or the rear window defroster of a car are practical examples of this electric heating

Inside many electronic devices is a ______ board with many small cylinders. These cylinders are resistors that help control ______ and ______ in the circuit. The colored bands on the resistors indicate their _______ values

A resistor whose resistance changes in response to _______ circumstances can be used as a sensor. The resistance of this night-light sensor changes when ______ strikes it. A ______ detects this change and turns off the light during the day

For the ideal-wire model, two wires are connected to a resistor. 
For an ideal wire: 
R = ____
ΔV_wire = ____ = ____
For the resistor R: 
ΔV_resistor = _______
This is the amount of _______ drop across the resistor

Label the diagram 

a) The current is ______ along the wire-resistor-wire combination

b) In the ideal-wire model, there is no ______ drop along the wires. All the voltage drop is across the ______

Current moves in the direction of _______ potential, so there is a ______ drop when the current passes through the resistor _____ to _____.
The electric field in a resistor carrying a current in a circuit is _______. The strength of the electric field is: 
E = ____
Label the diagram 

The electric field inside the resistor is ______ and points from ______ to _____ potential 
The current is in the direction of _______ potential

Consider the circuits shown and assume the wires have no resistance. 
In reality, there is also an _______ resistance, r, in the battery, where terminal voltage is NOT equal to the _____

Consider the circuit diagram
The battery within the dashed rectangle is modeled as an ideal, _____-resistance source of emf in series with the internal resistance r
The terminal voltage is:
ΔV = ______
The emf is then: 
ε = ____ + ____
Solving for current gives: 
I = _______
Which shows that the current in this simple circuit depends on both the _______ (__) _______ to the battery and the ________ _______ (__)

Batteries connected one after the others are in ______. The total potential difference is the sum of the ________ ________ of each battery

A battery not only supplies a potential difference but also supplies ________. The charge escalator transfers the _______ _______ to the electric potential energy (U) of the charges. That energy is then _______ as the charges move through the lightbulb, keeping the filament warm and glowing.

Chemical energy in the battery is transferred to ______ ______ of the charges in the current. The charges lose energy in ______ as they pass through the filament of the bulb. This energy is transformed into the ______ energy of the glowing filament 

A charge q gains potential energy ΔU = ____ as it moves through a potential difference ΔV.
The potential difference of a battery is ΔV_bat = ___, so the battery supplies ΔU = ____
to charge q as it lifts the charge up to the charge escalator from the ______ to the ______ terminal.

Assume a circuit as shown. The rate at which the battery supplies energy is P_bat: 
P_bat = ____ = ____
The power delivered by source of emf is: 
P_emf = ____
SI unit: ____ = _____

In a single-resistor circuit, the battery's chemical energy is transferred to the _____ energy of the glowing filament (or resistor), raising its _______. 
State the order of energy transformation. What happens to energy at thermal energy?

1. Charge gains potential energy (U) in the _______. 
2. As charges accelerate in the electric field, ______ energy is transformed into _______ energy, in the resistor.
3. Collisions with atoms in the resistor transform the ______ energy of the charges into ______ energy (__) of the resistor

The current is the same in the battery and the resistor, so P_R = ____
The power dissipated in the resistor is exactly equal to the power supplied by the _______
The rate at which the energy is transferred from the current to the resistor is:
P_R = ___ = ___ = ___
Alternate forms of the power equation are 
P_R = ___ = ___ = ___