Physics unit 9 electricity
Does Induction apply to only Conductors, Insulators, or both?
Both
Are Fc & q1 directly or indirectly proportional?
Direct
Are Fc & q2 directly or indirectly proportional?
Direct
There is a value of __________________and _______________ at every point in space (empty or filled). There is _______________ and electric field strength can be determined when two charges are placed near each other.
Electric PE, electric potential, an electric force pushing/pulling on each charge
(Conductor or Insulator)? Rubber, plastic
Insulator
A Material with FEW free electrons
Insulators
An electric field has __________ & ____________
Magnitude and direction
Unit for Electric Potential
V (volt)
Unit for Potential Difference/ Voltage
V (volts)
Variable for charge
q
1e = ?
1.6x10^19C
Opposite charges __________ (attract or repel)?
Attract
Electric Field vectors point _____________________ positive charges.
Away
A negative charge creates an electric field. The direction of the electric field would be ____. a. dependent upon whether the test charge is positive or negative b. towards the negative charge c. away from the negative charge d. none of these
B
If the voltage across a circuit is tripled, then the current through the circuit would be ____. a. one-third as much b. three times as much c. unchanged
B
If you comb your hair and the comb becomes positively charged, your hair becomes A. positively charged. B .negatively charged. C. uncharged.
B
As more and more resistors are added in parallel to a circuit, the equivalent resistance of the circuit ____ and the total current of the circuit ____. Choose an answer for each blank. a. increases b. decreases c. stays the same
B, a
Does Polarization apply to only Conductors, Insulators, or both?
Both
For an isolated negative charge, electric field lines point in which direction? a. Downward due to gravity b. Both directions C. Toward the charge D. Away from the charge
C
The electrical force between two objects depends on the ___ and ___ the objects. a. mass of; distance between b. mass of; size of c. charge on; distance between d. charge on; size of e. mass of; charge on
C
Two neutral objects - object A and object B - are rubbed together. During the process, object A becomes charged positively and object B becomes charged negatively. This is because ______. a. protons are transferred from object B to object A. b. protons are transferred from object A to object B. c. electrons are transferred from object A to object B. d. electrons are transferred from object B to object A. e. object A exchanges a proton for one of object B's electrons. f. object A exchanges an electron for one of object B's protons.
C
Which of the following will produce a uniform electric field? A. A positive point charge B. A negative point charge c. two oppositely charged parallel platesThis answer is correct. d. None of these
C
How are INSULATORS charged?
Can be charged via Close contact (friction) and polarization
How are CONDUCTORS charged?
Can be charged via brief contact and induction and polarization
Continuous flow of charge through through a closed loop wire
Circuit
What are the requirements for an electric current to flow through a circuit?
Closed Loop wire, an energy source, an electric PE difference/voltage (delta V)
The amount of PE per charge that a small +ve test charge has when placed at a point in space (Unit: Volts)
Electric potential
the energy stored in an electric field due to charge's location/position in an Electric Field (Units of J)
Electrical potential energy
Halving the distance (i.e., decreasing by a factor of two) between two charged objects will cause the electrical force between them to be ___ the initial force. a. the same as b. twice c. one-half d. three times e. one-third f. four times g. one-fourth
F
- lines connecting a series of "E" vector arrows - show the direction of the "E" vector, but not the magnitude
Field lines
The electrical force between two objects is 36 N. If the distance between the objects is cut in half, the force between them will be ___. a. 4 N b. 9 N c. 12 N d. 18 N f. 72 N g. 108 N h. 144 N
H
Symbol for Current
I
How are voltage, current, and resistance in a circuit related?
I=deltaV, I= 1/R
Differences between Coulomb's Law (Fc) & Law of Universal Gravitation (Fg)
In Coulomb's law, Fc includes both attractive and repulsive interactions between 2 Charges. In LoG, Fg includes only attractive forces between 2 objects with Mass.
c
In a parallel circuit, A. If one device fails, the current in the other devices will increase B. If one device fails the resistance in the other devices will increase C. If one device fails, the current will continue to flow through the other devices, unchanged D. If one device fails, the current in the whole circuit will stop
If a +ve charge is moved AWAY from negative source charge, its PE & V ____________ (increases/decreases).
Increases
Are Fc & r^2 directly or indirectly proportional?
Indirect
Unit for Electrical PE
J (joules)
Unit for Electric Field
N/c (force per charge)
-ve = ?
Negative charge
What is the pathway that charges flow through in a circuit?
Negative charges flow from the negative terminal to the positive terminal (opposite of the Conventional flow"
The charge on a electron (Qe) is..
Qe=1.6x10^19C
Equation for Net Charge
Qnet = (Np x Qp) + (Ne x Qe)
The charge on a proton (Qp) is.....
Qp= 1.6x10^19C
Symbol for Resistance
R (capital)
Like charges ___________ (attract or repel)?
Repulse 111
Measures the difficulty or hindrance of charge flow through a device
Resistance
Is Charge (q) a scalar or vector?
Scalar
- All devices are objected in a continue loop - if one device fails, all devices fail
Serie circuit
Where do Electric Fields come from?
Source charges (Q)
What 2 things does the Strength of an Electric Field depend on?
The source charge and distance of separation from the charged object
What is the elementary charge, "e"?
The value of 1.6 x 10^-19 C
Electric Field vectors point _____________________ negative charges.
Toward
True or False? Empty AND Filled Space has an Electric Field
True
True or False? In a circuit, The positive terminal does work in moving a charge around the circuit.
True
True or False? The direction of the electric field depends on the charge (positive or negative).
True
True or False? The number of field lines is proportional to the source charge.
True
True or False? When the Electric Field does work on q, its potential energy changes.
True
Is an Electric Field a vector or Scalar?
Vector
Potential Difference (ΔV) is also known as ______
Voltage
The amount of PE charges lose as they move betweeen 2 points on a circuit
Voltage
Qp = ?
+e
Qe = ?
-e
If the resistance of a circuit is quadrupled, then the current through the circuit would be ____. a. one-fourth as much b. four times as much c. unchanged
A
Inn a good insulator, electrons are usually A. able to move in a straight line. B. free to move around easily. C. unable to freely move. D. semi-free to move around
A
Which of the following would cause the electrical force between two objects to increase? Choose all that apply. a. increase the charge on one object b. increase the charge on both objects c. increase the mass of one object d. increase the mass of both objects e. increase the distance between the objects' centers f. decrease the distance between the objects' centers
A,b, f
Which of the following will cause the current through an electrical circuit to decrease? Choose all that apply. a. decrease the voltage b. decrease the resistance c. increase the voltage d. increase the resistance
A,d
Unit for Current
Ampheres (A)
(Conductor or Insulator?) Human body, metal
Conductor
a material with MANY free electrons.
Conductors
Does Induction apply to only Conductors, Insulators, or both?
Conductors only
Unit for charge
Coulomb
What other names do Attractive/Repulsive Forces go by?
Coulombs force, electrostatic force, electric force
The rate at which charge flows through an electrical device
Current
What does "It", "Rt" and "Vt" stand for
Current total, resistance total, and voltage total
A positive charge moves through a uniform electric field, and the electric field does negative work on the charge. Has the charge gained potential energy or lost potential energy? a. lost because the charge moved against the field lines B. Lost Because the charge moved with the field lines C. gained because the charge moved with the field lines d. gained because the charge moved against the field lines
D
A positive charge moves through a uniform electric field, from a location of lower electric potential (V) to a location of higher electric potential (V). Has the charge moved with the field, against the field, or perpendicular to the field? A. with the field, because the charge has moved toward the positive plate B. against the field, because the charge has moved toward the negative plate C. perpendicular to the field D. Against the field, because the charge has moved toward the positive plate E. with the field because the charge has moved toward the negative plate
D
A positive charge moves through a uniform electric field, from a location of lower electric potential (V) to higher electric potential (V). The electric field has done ___. A. positive work on the charge, because the charge moved toward the positive plate B. positive work on the charge, because the charge moved away from the positive plate C. negative work on the charge, because the charge moved away from the positive plate D. negative work on the charge, because the charge moved toward the positive plate
D
Doubling the distance between two charged objects will cause the electrical force between them to be ___ the initial force. a. the same as b. one-half c. one-third d. one-fourth e. twice f. three times g. four times
D
If a +ve charge is moved TOWARD from negative source charge, its PE & V ____________ (increases/decreases).
Decreases
If a positive charge in a uniform electric field (shown above) moves against the field, the work done to move the charge would be __________________ (positive/negative), the potential difference would be __________________ (positive/negative), and the potential energy of the charge would __________________ (increase/decrease). The charge would be moving to a location of __________________ (higher/lower) electric potential.
Negative, positive, increase, higher
Is the "Conventional" flow of charge accurate today?
No
The electric potential difference between 2 points on a circuit is equal to the product of the current and total resistance
Ohm's law
Unit of Resistance
Ohms
Potential difference (ΔV) measures how much __________________ charges lose as they move between two points on a circuit.
PE
- defies are connected via individual branches so each device has a different pathway for charges to flow - If one device fails, the other devices continue to work
Parallel circuit
Net electric charge is restricted to certain allowed values (integer multiples of e).
Polarization of charge
+ve = ?
Positive charge
Describe the conventional flow of charge in a circuit
Positive charges flow from positive terminal to negative terminal
If a positive charge in a uniform electric field (shown above) moves with the field, the work done to move the charge would be _________________ (positive/negative), the potential difference would be __________________ (positive/negative), and the potential energy of the charge would __________________ (increase/decrease). The charge would be moving to a location of __________________ (higher/lower) electric potential.
Positive, negative, decrease, lower
What are the 2 forms of charges? Which particles carry which charge?
Positve and negative. Protons are positive & electrons are negative
Change in potential - the work done per charge
Potential difference (delta V)
What do Electric fields do?
Push charges (q)