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Questions and Answers
A coulomb of charge that passes through a 6-volt battery is given
A coulomb of charge that passes through a 6-volt battery is given
- 6 newtons
- 6 joules (correct)
- 6 watts
- 6 ohms
- 6 amperes
Which statement is correct?
Which statement is correct?
- Voltage flows through an open or closed circuit
- Charge flows in a close circuit (correct)
- Resistance flows through an open circuit
- Current is the primary cause of voltage
Electrons move in an electrical circuit
Electrons move in an electrical circuit
- By being bumped by other electrons
- By colliding with molecules
- By interacting with an established electric field (correct)
- Because the wires are so thin
- None of the above
Heat a copper wire and its electric resistance
Heat a copper wire and its electric resistance
Stretch a copper wire so that it is thinner and the resistance between it
Stretch a copper wire so that it is thinner and the resistance between it
The primary source of electrons in an ordinary electric circuit is
The primary source of electrons in an ordinary electric circuit is
The source of electrons lighting an incandescent AC lightbulb is
The source of electrons lighting an incandescent AC lightbulb is
A woman experiences an electric shock. The electrons making the shock come from the
A woman experiences an electric shock. The electrons making the shock come from the
In a common DC circuit, electrons move at speeds of
In a common DC circuit, electrons move at speeds of
When a light switch is turned on in a DC circuit, the average speed of electrons in the lamp is
When a light switch is turned on in a DC circuit, the average speed of electrons in the lamp is
Modern automobile headlights are connected in
Modern automobile headlights are connected in
There are electrons in the filament of the AC lamp in your bedroom. When you turn on the lamp and it glows, the glowing comes from
There are electrons in the filament of the AC lamp in your bedroom. When you turn on the lamp and it glows, the glowing comes from
A 100-watt lamp glows brighter than a 25-watt lamp. The electrical resistance of the 100-watt lamp must be
A 100-watt lamp glows brighter than a 25-watt lamp. The electrical resistance of the 100-watt lamp must be
In an electric circuit, the safety fuse is connected to the circuit in
In an electric circuit, the safety fuse is connected to the circuit in
When a pair of 1-ohm resistors are connected in series, their combined resistance is
When a pair of 1-ohm resistors are connected in series, their combined resistance is
A capacitor is used to store
A capacitor is used to store
The number of electrons delivered daily to an average American home by an average power utility in the mid 1980s was
The number of electrons delivered daily to an average American home by an average power utility in the mid 1980s was
Two lamps, one with a thick filament and one with a thin filament, are connected in series. The current is greater in the lamp with the
Two lamps, one with a thick filament and one with a thin filament, are connected in series. The current is greater in the lamp with the
Two lamps, one with a thick filament and one with a thin filament, are connected in parallel to a battery. The voltage is greatest across the lamp with the
Two lamps, one with a thick filament and one with a thin filament, are connected in parallel to a battery. The voltage is greatest across the lamp with the
Two lamps, one with a thick filament and one with a thin filament of the same material, are connected in parallel to a battery. The current is larger in the lamp with the
Two lamps, one with a thick filament and one with a thin filament of the same material, are connected in parallel to a battery. The current is larger in the lamp with the
Compared to the resistance of two resistors connected in series, the same two resistors connected in parallel have
Compared to the resistance of two resistors connected in series, the same two resistors connected in parallel have
If you plug an electric toaster rated at 110 V into a 220-V outlet, the current in the toaster will be about
If you plug an electric toaster rated at 110 V into a 220-V outlet, the current in the toaster will be about
When a 60-watt light bulb is connected to a 120-volt source the current in the light bulb is
When a 60-watt light bulb is connected to a 120-volt source the current in the light bulb is
If 0.8 A of current flows through a light bulb connected to a 120 V outlet, the power consumed is
If 0.8 A of current flows through a light bulb connected to a 120 V outlet, the power consumed is
The headlights, radio, and defroster fan in an automobile are connected in
The headlights, radio, and defroster fan in an automobile are connected in
Compared to the filament thickness of a 60 W light bulb, the filament of a 100 W light bulb will be
Compared to the filament thickness of a 60 W light bulb, the filament of a 100 W light bulb will be
Compared to a single lamp connected to a battery, two identical lamps connected in series to the same battery will carry
Compared to a single lamp connected to a battery, two identical lamps connected in series to the same battery will carry
Compared to a single lamp connected to a battery, two lamps connected in parallel to the same battery will carry
Compared to a single lamp connected to a battery, two lamps connected in parallel to the same battery will carry
An electric heater is rated at 300 W when used in a 110-V circuit. The safety fuse in the circuit can handle 15 A of current. How many heaters can be safely operated in the circuit?
An electric heater is rated at 300 W when used in a 110-V circuit. The safety fuse in the circuit can handle 15 A of current. How many heaters can be safely operated in the circuit?
A heater uses 20 A when used in a 110-V line. If electric power costs 10 cents per kilowatt hour, the cost of running the heater for 10 hours is
A heater uses 20 A when used in a 110-V line. If electric power costs 10 cents per kilowatt hour, the cost of running the heater for 10 hours is
Connect a pair of lamps in series and you draw current from the connected battery. Connect the same lamps in parallel and you draw
Connect a pair of lamps in series and you draw current from the connected battery. Connect the same lamps in parallel and you draw
Three resistors, 1-ohm, 2-ohm, and 3-ohm are connected in parallel. If they were connected in series instead their equivalent resistance would be
Three resistors, 1-ohm, 2-ohm, and 3-ohm are connected in parallel. If they were connected in series instead their equivalent resistance would be
The ratio of the potential difference across a metallic conductor to the current in the conductor is known as
The ratio of the potential difference across a metallic conductor to the current in the conductor is known as
What condition must exist between two points in a conductor in order to maintain a flow of charge?
What condition must exist between two points in a conductor in order to maintain a flow of charge?
Study Notes
Electric Current Concepts
- A coulomb of charge passing through a 6-volt battery provides 6 joules of energy.
- Charge must flow in a closed circuit; voltage can exist in both open and closed circuits.
- Electrons in an electric circuit primarily move due to interaction with an established electric field.
- Heating a copper wire increases its electric resistance.
- Stretching a copper wire results in increased resistance due to its reduced thickness.
Sources and Flow of Electrons
- The primary source of electrons in an electric circuit is the circuit itself (e.g., batteries).
- Electrons illuminating an incandescent light bulb originate from atoms in the filament.
- Electric shocks experienced by individuals are due to electrons from their bodies.
Movement and Speed of Electrons
- In common DC circuits, electrons move at speeds of a fraction of a centimeter per second.
- When a light switch is engaged, the average speed of electrons in a lamp is less than 1 cm/s.
Circuit Configurations
- Modern automobile headlights are wired in parallel for consistent brightness.
- When a lamp glows, it is due to the same electrons that flow through the circuit, not different ones.
- A higher wattage lamp (100-watt) has lower resistance compared to a lower wattage lamp (25-watt).
Current and Resistance in Resistors
- Safety fuses are incorporated in series with the electrical circuit to protect against overload.
- Two 1-ohm resistors in series yield a total resistance of 2 ohms; in parallel they give 0.5 ohms.
- Capacitors are capable of storing both charge and energy.
Power Consumption and Safety
- In the mid-1980s, average daily electron delivery to an American home was in the billions.
- Comparing filament thickness, a 100-watt bulb has a thicker filament than a 60-watt bulb.
- The voltage across parallel-connected lamps remains constant, regardless of filament thickness.
Electrical Ratings and Calculations
- If a toaster rated at 110 V is plugged into a 220 V outlet, the current will be about twice what it is intended to be.
- A 60-watt bulb connected to a 120-volt source draws 0.5 A of current.
- A light bulb drawing 0.8 A from a 120 V outlet consumes 96 watts of power.
Current Flow in Parallel and Series
- Automotive accessories like headlights and radios are connected in parallel with individual switches for control.
- In a series configuration, current is the same across all components while it varies in parallel circuits.
- Connecting identical lamps in series reduces the overall current compared to a single lamp.
Resistance in Series vs. Parallel
- Two identical lamps in parallel draw more current than one lamp in series due to available voltage across both.
- In a series connection, the equivalent resistance of three resistors (1-ohm, 2-ohm, and 3-ohm) would total 6 ohms, making it 9 times greater than their parallel configuration.
Concepts of Voltage and Current
- The ratio of potential difference (voltage) to current is known as resistance.
- For charge flow in a conductor, no special conditions like a magnetic field or a high resistance need to be present—just a potential difference.
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Description
Test your knowledge of electric current concepts from Chapter 23 of Conceptual Physics. This quiz includes multiple-choice questions that focus on definitions and principles related to circuits and charges. Challenge yourself and enhance your understanding of how current behaves in different scenarios.
