# Electricity And Magnetism

## Unlock all answers in this set

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How does increasing the distance between charged objects affect the electric force between them?
The electric force decreases because the distance has an indirect relationship to the force.
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Two balls are placed near one another and hang down, as shown below. Which conclusion is supported by this evidence?
Neither ball has a charge.
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As Chelsea removes her clothes from the dryer, she sees sparks, which are examples of .
static discharge
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The area around a charged object where the object can exert a force on other charged objects is an electric .
field
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An electroscope is a device that detects charge on objects that touch it or are brought near it. John rubs a piece of cotton fabric on a plastic rod and then touches the rod to the electroscope. What methods of charging does John use?
John charges the rod through friction, then charges the electroscope through conduction
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Which change increases the electric force between objects?
Electrons are added to two negatively charged objects.
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Alfredo makes a diagram to organize his notes about charging objects. Which statement should he place in the region marked X?
The objects have the same charge.
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The diagram shows two charged objects, X and Y. Based on the field lines, what are the charges of the objects?
X: positive Y: positive
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A positively charged object will attract an object that has .
negative charge
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Tisa makes a diagram to organize her notes about charging objects. Which statement should she place in the region marked X?
Electrons move between objects.
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Hiro rubs an inflated balloon on his hair, and his hair sticks to the balloon. As he moves the balloon away from his head, how does the electric force change?
The electric force decreases because the distance increases.
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How does increasing the amount of charge on an object affect the electric force it exerts on another charged object?
The electric force increases because the amount of charge has a direct relationship to the force.
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For which pair of objects would adding the same amount of electrons to each object result in a decrease in the electric force?
two positively charged objects
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Which factors affect the strength of the electric force between two objects?
the distance between the objects and the amount of charge on the objects
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Measurements of two electric currents are shown in the chart. Which best compares the two currents?
Current Y has a greater potential difference, and the charges flow at a slower rate.
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The chart shows the voltage of four electric currents. Which is best supported by the data in the chart?
Current X has a lower potential difference than Current Y.
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Nina is working with electricity and shortens the wires through which the current is flowing. What is Nina most likely trying to accomplish?
decrease resistance
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Electric current flows through paths called circuits. People often build circuits using wires, resistors, and batteries. A battery is a voltage source. A circuit with which components has a current with the greatest voltage?
wires, a 9V battery, no resistors
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Which two wire properties would provide the greatest resistance to the flow of a current?
long, thin
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In the diagram, the arrow shows the movement of electric charges through a wire connected to a battery. What causes the electric charges to flow from one end of the battery to the other?
a difference in electric potential
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What is required for an electric charge to flow through a wire?
a difference in electric potential
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Jodi made a list about electric current to help her study for a test. 1) Movement of electrons is continuous in a current. 2) Electrons move from areas of low to high electric potential. 3) Voltage causes current to flow. 4) Rate at which current flows is measured in amperes. Which best describes Jodi's error?
Electrons move from areas of high to low electric potential.
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Cora, an electrician, wraps a copper wire with a thick plastic coating. What is she most likely trying to do?
keep a current from passing out of the wire
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Which most likely has the greatest conductivity?
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What would decrease the resistance of wires carrying an electric current?
short wires
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Electric current is the flow of charged particles called
electrons
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Why is copper used for most electrical wiring?
It is a good conductor.
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Resistance depends on which properties of a wire? Check all that apply.
thickness length temperature
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When the resistance in a circuit remains constant, how are the voltage and current related?
The current doubles when the voltage doubles because they are directly proportional.
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Which statement describes the relationship of voltage and current?
Voltage is directly proportional to current because I = V/R
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What is the resistance of a light bulb if a potential difference of 120 V will produce a current of 0.5 A in the bulb?
240
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A light bulb has a resistance of 360 . What is the current in the bulb when it has a potential difference of 120 V across it?
0.33 A
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Which symbol and unit of measurement are used for electric current?
symbol: I; unit: A
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According to Ohm's law, which combination of units is the same as the unit for resistance?
volt ÷ ampere
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To increase the current in a circuit, the ____ can be increased.
voltage
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Which equation is correct according to Ohm's law? Check all that apply.
V = IR I = V/R
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Aretha measures a circuit at 110 V and 240 . Using Ohm's law, what can she calculate for the circuit?
current
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Which symbol and unit of measurement are used for voltage?
symbol: V; unit: V
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To increase the current in a circuit, the ______ can be increased.
voltage
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Which statement describes the relationship of resistance and current?
Resistance is inversely proportional to current because R = VI.
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An electric circuit can have no current when a switch is
open
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What is the main disadvantage of parallel circuits?
They are complicated to design and build.
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Which statement describes an open circuit?
The circuit is incomplete and broken, and the lights in the circuit do not shine.
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Roshan describes the basic parts of an electric circuit using a shower as a model. Which part of a circuit does the water pipe represent?
the wire
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Which statements describe a closed circuit? Check all that apply.
Bulbs will shine. The circuit is complete. Charges flow.
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Linus builds an electrical circuit with a battery and with wires that carry the current. As the battery weakens, the current also weakens. How does this affect the magnetic field around the wires?
The field gets weaker
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What is the Compact Muon Solenoid used to study?
the particles emitted when atoms collide
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A(n) _______ is produced around a wire when an electrical current is in the wire.
magnetic field
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What happens to an iron bar when it is placed within the coils of a solenoid?
It becomes a magnet.
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Frances drew a diagram to show electromagnetic induction. Which label belongs in the area marked X?
Magnetic field
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What affects the direction of the current moving through a wire? Check all that apply.
the direction the wire moves in the direction of the magnetic field
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Maya sets up two experiments as shown. What question is Maya most likely trying to answer?
How does the thickness of the wire affect the strength of an electromagnet?
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Juan makes an adjustment to an electromagnet that causes the electromagnet to lose some of its strength. What did Juan most likely do?
He reduced the number of loops in the wire.
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Which wire, when current flows through it, would be surrounded by the strongest magnetic field?
the one with the most coil things
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The diagram shows a setup for inducing a current in a wire. Which change would cause the needle on the ammeter to point to the left of the zero?
moving the wire downward through the magnetic field
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What is the function of the slip rings in an electric generator?
producing a path for current to flow
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The left side of the armature in an electric motor is pushed down. When the current changes direction, how is the motion of the armature affected?
It is pulled up on the right side.
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Rob is studying for an exam. He listed some properties of magnets in a Maglev train. Which best explains Rob's error?
The repelling of the support magnet decreases friction.
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Which best contrasts electric doorbells and audio speakers?
Speakers involve rapid changes in the direction of current, and doorbells do not.
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The picture shows a basic diagram of an electric motor. Which labels best complete the diagram?
X: Armature Y: Brush Z: Commutator
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Which uses direct current?
flash light
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Laptop computers are made with batteries, but they must also be plugged into outlets to charge the batteries. Which is true regarding laptops?
They can run on either direct or alternating current.
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What is the function of an electromagnet in an electric doorbell?
It attracts a metal striker, which then hits the bell.
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What causes the poles of the electromagnet in an audio speaker to repeatedly switch directions?
a current that rapidly switches direction
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X: Use DC Y: Use AC
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The diagram shows the set-up for an electric doorbell. Which best explains why the bell would not ring in this set-up?
The circuit is open.
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An electric generator converts kinetic energy into ____energy.