Electricity (3rd Unit) Lesson: Physics B
What is the current in a circuit with a 9.0 V battery and a resistance of 36.0 Ω?
0.25 A
A series circuit contains a 30 Ω resistor, a 20 Ω resistor, and a 10 Ω resistor. The power supply provides 100 V to the circuit. The current in the 10 Ω resistor, to two significant figures, is __ A.
1.7
A charge of 24 µC is at a location where the electric potential is 8.0 V. What is the electric potential energy of the charge?
1.9 × 10^-4 J
A 7.2 × 10^-5 C charge has an electric potential energy of 1.08 × 10^-2 J. The electric potential, to the nearest whole number, is ___ V.
150
A ceiling fan draws a current of 0.625 A and has a voltage of 120 V. The resistance of the ceiling fan, to the nearest whole number, is Ω.
192
A proton is moved from a position where the electric potential is 125 V to a position where the electric potential is 275 V. The magnitude of the charge on a proton is 1.602 × 10^-19 C. What is the change in electric potential energy of the proton?
2.4 × 10^-17 J
The strength of the electric field 0.5 m from a 6 µC charge is _______N/C. (Use k = 8.99 × 109 N• (m^2/C^2) and round answer to the nearest whole number.)
215760
A power source that provides a current of 1.6 A to two 5 Ω resistors connected in series is moved to a parallel circuit that consists of three identical resistors. In the parallel circuit, the overall current is 2.0 A. The value of a resistor used in the parallel circuit is __ Ω.
24
A proton is moved so that its electric potential energy increases from 2.0 × 10-18 J to 6.0 × 10-18 J. The magnitude of the charge on a proton is 1.602 × 10-19 C. The electric potential difference through which the proton moved, to the nearest whole number, is __ v
25
A source charge generates an electric field of 4286 N/C at a distance of 2.5 m. What is the magnitude of the source charge? (Use k= 8.99 x 10^9 N (m^2/C^2))
3.0 µC
What is the electric potential energy of a charge that experiences a force of 3.6 × 10^-4 N when it is 9.8 × 10^-5 m from the source of the electric field?
3.5 × 10^-8 J
What is the value of the charge that experiences a force of 2.4 × 10^-3 N in an electric field of 6.8 × 10^-5 N/C?
3.5 × 10^1 C
A circuit carries a current of 0.64 A when there is a resistance of 50.0 Ω. The voltage applied to the circuit, to the nearest whole number, is __ V.
32
What is the electric field between two parallel plates if the electric potential difference between the plates is 24 V and the plates are 65 mm apart?
369 N/C
A series circuit contains three 2 Ω resistors and a 6 Ω resistor. The current in each resistor is 4.0 A. What is the voltage of the battery in the circuit?
48 V
What is the electric potential at a distance of 1.2 m from a 7.5 µC point charge?
5.6 × 10^4 V
A charge of +0.08 C moves to the right due to a 4 N force exerted by an electric field. What is the magnitude and direction of the electric field?
50 N/C right
The magnitude of the electrical force acting between a +2.4 × 10^-8 C charge and a +1.8 × 10^-6 C charge that are separated by 0.008 m is __ N, rounded to the tenths place.
6.1
The electric field between two parallel plates has a magnitude of 1250 N/C. The positive plate is 0.05 m away from the negative plate. The electric potential difference between the plates, rounded to the tenths place, is ___ V.
62.5
Which are disadvantages of series circuits? Check all that apply.
A break in one wire causes all current to stop. If one bulb goes out, the others go out.
How does charging by conduction occur?
A charged object touches a neutral object.
Which statement correctly describes the formation of an electric current?
A voltage causes electric charges to move from higher to lower potential.
Roland writes a story in which boaters become stranded on a sandy island. In the story, they set about collecting materials to create semiconductors to repair computer components in their radio. Which problem is likely to be the most difficult for Roland's characters to overcome?
Any substances they find are too impure.
The diagram shows the electric field due to point charge Q. The negative charge, A, is within the field. Which statements are correct? Check all that apply.
Charge Q is negative. The electric field is nonuniform. If charge A is negative, it moves away from charge Q.
Which type of circuit is a continuous loop that allows the flow of current along its intended path?
Closed
What formula gives the strength of an electric field, E, at a distance from a known source charge?
E = kq/d^2
A point charge is used to determine the electric field around a charged particle. Why is it necessary that the point charge does not affect the position of the charge being tested?
Electric fields are inversely proportional to the square of the distance, so any change in position changes the field.
How are electric potential difference and electric potential energy related?
Electric potential difference is the difference in electric potential energy divided by the charge.
When studying atoms, scientists can ignore the ______ force between charged particles that make up the atoms because it is many millions of times smaller than other forces in the atom.
Gravitational
Which equation relates charge, time, and current?
I = Δq/t
How does the electrical force relate to the charge of an object?
It is directly proportional to the charge.
Farha makes the graphic organizer shown to review the characteristics of transistors. Which statement belongs in the region marked X?
It is made from three layers of semiconductors.
How does a rubber rod become negatively charged through friction?
It is rubbed with another object, and electrons move onto the rod.
Marta, Cato, and Juan plan a skit to illustrate one of the methods of charging. Marta and Cato are walking together. Each has one flower and one box of candy. Juan offers Cato a huge bouquet of flowers, but Cato can't take it because his hands are full. Cato hands his flower to Marta and then turns to Juan to take the bouquet. Marta walks away in one direction with two flowers and one box of candy. Juan keeps the bouquet and walks away in the other direction. Cato looks sad standing alone with only a box of candy. How does the skit model a method of charging?
It models induction because the offer of flowers represents a charged object that causes an electron (a flower) to transfer from one object to another.
Which best describes an example of a p-type semiconductor?
It uses boron so that electrical conduction is due to the movement of a positive charge.
Which best describes the electric field created by a positive charge?
Its rays point away from the charge.
Jason makes a graphic organizer for insulators and conductors and wants to add the following labels to it. Label 1: Lacks free electrons Label 2: Aluminum In which regions should Jason place each label?
Label 1: X Label 2: Z
Maria makes a graphic organizer to compare open, closed, and short circuits. She adds the labels shown. Label 1: Current flows in the circuit. Label 2: This forms when a bulb burns out. In which region should she place each label?
Label 1: Y Label 2: W
What is the direction of the electric field at a point directly to the left of a positive charge, Q?
Left
How does charging by conduction compare with charging by induction?
Oppositely charged objects form in induction but not in conduction.
Based on the locations of the elements aluminum (Al), silicon (Si), and phosphorus (P) on the periodic table, which lists the elements in order from the least conductive to the most conductive?
P, Si, Al
A positive rod is placed to the left of sphere A, and the spheres are separated. Which best describes the spheres?
Sphere A is negative and sphere B is positive because electrons from sphere B are attracted to the rod and move to sphere A.
The diagram shows a transistor used in a circuit. The transistor in the circuit is used to
Switch a current
Jason sees a news report about a traffic jam caused by a truckload of tires that spilled across the road. The next day in class, he uses the traffic jam as an analogy to explain electric circuits to his friend. Which is most likely the analogy that Jason used?
The cars represent moving charges, and the spilled tires represent an increased resistance that causes the current to decrease.
A negative test charge experiences a force to the right as a result of an electric field. Which is the best conclusion to draw based on this description?
The electric field points to the left because the force on a negative charge is opposite to the direction of the field.
The table lists the values of the electrical force and the gravitational force between two protons. How do the electrical force and the gravitational force compare?
The electrical force is 1.2 × 10^36 times greater than the gravitational force.
The table lists the values of the constants used to calculate the electrical force and the gravitational force Which best explains how the constants affect the electrical and gravitational forces?
The electrical force is much larger than the gravitational force because 109 is much greater than 10^-11.
A neon light consists of a glass tube with metal wires at each end. When connected to a high-voltage source, the gas glows. If a fly lands on the glass tube, what will most likely happen?
The fly will not feel a shock because the glass insulates it from the electrons in the gas and the metal.
How do the charges compare when two objects are charged through friction?
The objects become oppositely charged and have equal amounts of charge.
The cause of a fire in a computer is described as an incorrectly wired circuit. Which statement best explains the likely cause of the fire?
The wiring contained a short circuit, so the reduced resistance caused an increase in current.
Both the electrical force and the gravitational force between two objects share which relationship?
They are inversely proportional to the square of the distance.
Which statement best describes the relative conductivity of semiconductors?
They are more conductive than nonmetals but less conductive than metals.
The diagram shows a transistor. Which explains whether boron or arsenic is the dopant most likely used in the semiconductor layer marked with +?
This layer is the emitter of a PNP transistor, so it could include boron.
Which equations should be used only in a uniform electric field? Check all that apply.
U = qEd △ V = Ed
What is the direction of the electric field at a point directly below a negative charge, Q?
Up
What is the abbreviation for the SI unit for electric potential?
V
Which equation is used to calculate the electric potential in an electric field from a point charge?
V = kq/d
For a constant resistance, how is the voltage related to the current?
Voltage is directly proportional to current, so when the voltage doubles, the current doubles.
Charges of +2 µC and +3 µC are 4 mm from each other. Raina's group draws four diagrams trying to represent the electrical force between the charges. Which diagram is correct?
W
Three charges are located at the vertices of a triangle, as shown. Which vector best represents the net force acting on the -3 C charge in the diagram?
W
The diagram shows the electric field around two charged objects. What are the correct labels for the image?
W: Negative X: Negative
Bruce collects the data on four electric circuits listed in the table. Bruce must report any circuits that deliver more than 4.0 C of charge in 8.0 s. Which lists every circuit that Bruce must include in his report?
X and Z
Kiki makes a table to compare the particles in a magnesium atom to those in a magnesium ion. She knows that a magnesium ion has an electric field that points away from the ion. What values should she use to complete her table?
X: 12 Y: 12 Z: 10
Mark creates a graphic organizer to review his notes about electrical force. Which labels belong in the regions marked X and Y?
X: Decreasing to half will quadruple force Y: Doubling will double force
An electric field around two charged objects is shown. What are the charges of objects X and Y?
X: positive Y: negative
Wendy makes a graphic organizer to help herself apply Ohm's law to electric circuits. Which formulas belong in the regions marked X and Y?
X:R subeq = R sub1 + R sub2 + R sub3 Y: I = V/R subeq
The diagram shows a charge moving into an electric field. The charge will most likely leave the electric field near
Y
The table lists the time it takes for an amount of charge to pass through a point in a wire. Janelle is exploring the relationship between the brightness of a light bulb and the current that powers it. When applying these currents to the same bulb, the bulb is brighter when the current is greater. Which lists the currents in the order of the bulb brightness they cause from most bright to least bright? Brightness = Charge / Time
Y, W, Z, X
This circuit diagram lacks a basic feature of a circuit. Which basic feature is missing from the circuit?
a device that uses energy
Electric field lines can never cross. What would crossed electric field lines indicate?
a field pointing in two directions
Which best describes the materials that make up an electrical cord?
a metallic conductor with free electrons surrounded by a rubber insulator lacking free electrons
After hearing about an accident on his normal route, Mr. Gujral checks for alternate routes to get to work. What type of circuit does this traffic situation model?
a parallel circuit because there is more than one path
An electric field is represented by the force on which particle?
a positive test charge
What is the unit for measuring electric current?
ampere
Which is a dopant for a semiconductor that conducts electricity due to the movement of electrons?
antimony
Angela sees a puzzle that uses a board with 20 holes drilled into it. There are 18 pegs in the holes, and the goal of the puzzle is to move the pegs by hopping them into the open holes until both holes are at one end of the board. How could Angela use the puzzle to model semiconductors?
as a p-type semiconductor with the pegs representing electrons and the holes representing positive charges
Liana draws a diagram to show the direction of the electric force acting on a charged particle in a uniform electric field. Which change would make the diagram correct?
changing the force to point right
Which factors affect the electrical force between two objects?
charge and distance between them
Through which element would someone most likely receive a shock?
chromium (Cr)
What can a transistor do in order to fulfill its function in a circuit? Check all that apply.
control its own semiconductance act like an insulator act like a conductor
What is the continuous flow of electric charge?
current
What is a path through which electric charges travel?
electric circuit
The area around a charged object that can exert a force on other charged objects is a(n) _________.
electric field
While solving a problem, Sue calculates an answer that has the units N*m/C. Which quantity did Sue find for her answer?
electric potential difference
Which is the work required to move a charge?
electric potential energy
Which lists the layers in a PNP transistor from the least negative to the most negative?
emitter, base, collector
The area around a charged object that can exert a force on other charged objects is an electric _____.
field
Which is a dopant for a p-type semiconductor?
indium
A material that restricts the flow of electricity or thermal energy is a(n) ______.
insulator
A positive charge, q1, of 5 µC is 3 × 10-2 m west of a positive charge, q2, of 2 µC. What is the magnitude and direction of the electrical force, Fe, applied by q1 on q2?
magnitude: 100 N direction: east
Jasmine makes a note card about series circuits. She records the points shown. Which change will correct the error on her note card?
moving point (2) into the Advantages column
A noncontinuous loop that prevents the flow of current is a(n) ____ circuit.
open
The direction of electrical force is based on the fact that like charges will _____ each other.
repel
A disrupted circuit in which the current bypasses its proper path is a(n) ______ circuit.
short
Which principle states that the net electrical force on a specific charge is equal to the sum of the vector components of the charges applying forces on it?
superposition principle
Which best describes the two main functions of transistors in circuits?
switching and amplifying
Which is a dopant for a semiconductor that conducts electricity due to the movement of positive charges?
thallium
Which quantities are equal to sum of the individual values within a circuit?
the current in a parallel circuit and the voltage in a series circuit
While teaching about transistors, Mrs. Kwon shows a video of a hand pump being used to draw water from a well. She points out how the person primes the pump by pouring a small amount of water into it before the water would start to flow. What does the water used to prime the pump represent?
the current in the base that turns the transistor on
The circuit diagram shows a circuit containing several different components. Which correctly describes the number of one type of component in this circuit?
three resistors
Tracy scuffs her socked feet across a carpet. When she touches a doorknob, she gets a small shock. How did Tracy become charged?
through friction between her feet and the carpet
Suchita sees this symbol shown in a circuit diagram. What is the purpose of the component represented by the symbol?
to measure voltage
A circuit component that is composed of a semiconductor layer sandwiched between two other semiconductor layers is a(n) __________.
transistor
Which pair does NOT have an electric force between them?
two neutral objects
Which changes would cause an increase in the resistance of a wire? Check all that apply.
using a thinner wire using a longer wire increasing its temperature
