Making connections: take-home investigation—filament observations
Find a lightbulb with a filament. Look carefully at the filament and describe its structure. To what points is the filament connected?
Section summary
Electric current
is the rate at which charge flows, given by
where
is the amount of charge passing through an area in time
.
The direction of conventional current is taken as the direction in which positive charge moves.
The SI unit for current is the ampere (A), where
Current is the flow of free charges, such as electrons and ions.
Drift velocity
is the average speed at which these charges move.
Electrical signals travel at speeds about
times greater than the drift velocity of free electrons.
Conceptual questions
Can a wire carry a current and still be neutral—that is, have a total charge of zero? Explain.
Car batteries are rated in ampere-hours (
). To what physical quantity do ampere-hours correspond (voltage, charge, . . .), and what relationship do ampere-hours have to energy content?
Why are two conducting paths from a voltage source to an electrical device needed to operate the device?
In cars, one battery terminal is connected to the metal body. How does this allow a single wire to supply current to electrical devices rather than two wires?
Why isn’t a bird sitting on a high-voltage power line electrocuted? Contrast this with the situation in which a large bird hits two wires simultaneously with its wings.
Problems&Exercises
What is the current in milliamperes produced by the solar cells of a pocket calculator through which 4.00 C of charge passes in 4.00 h?
0.278 mA
A total of 600 C of charge passes through a flashlight in 0.500 h. What is the average current?
What is the current when a typical static charge of
moves from your finger to a metal doorknob in
?
0.250 A
Find the current when 2.00 nC jumps between your comb and hair over a
time interval.
A large lightning bolt had a 20,000-A current and moved 30.0 C of charge. What was its duration?
1.50ms
The 200-A current through a spark plug moves 0.300 mC of charge. How long does the spark last?
(a) A defibrillator passes 12.0 A of current through the torso of a person for 0.0100 s. How much charge moves? (b) How many electrons pass through the wires connected to the patient? (See figure two problems earlier.)
(a) 0.120 C
(b)
A clock battery wears out after moving 10,000 C of charge through the clock at a rate of 0.500 mA. (a) How long did the clock run? (b) How many electrons per second flowed?
The batteries of a submerged non-nuclear submarine supply 1000 A at full speed ahead. How long does it take to move Avogadro’s number (
) of electrons at this rate?
96.3 s
Electron guns are used in X-ray tubes. The electrons are accelerated through a relatively large voltage and directed onto a metal target, producing X-rays. (a) How many electrons per second strike the target if the current is 0.500 mA? (b) What charge strikes the target in 0.750 s?
A large cyclotron directs a beam of
nuclei onto a target with a beam current of 0.250 mA. (a) How many
nuclei per second is this? (b) How long does it take for 1.00 C to strike the target? (c) How long before 1.00 mol of
nuclei strike the target?
(a)
(b)
(c)
Questions & Answers
I'm interested in biological psychology and cognitive psychology
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
effective communication can lead to improved outcomes in various settings, including personal relationships, business environments, and educational settings. By communicating effectively, individuals can negotiate effectively, solve problems collaboratively, and work towards common goals.
it starts up serve and return practice/assessments.it helps find voice talking therapy also assessments through relaxed conversation.
miss
Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
I am taking this course because I am hoping that I could somehow learn more about my chosen field of interest and due to the fact that being a PsyD really ignites my passion as an individual the more I hope to learn about developing and literally explore the complexity of my critical thinking skills
