Circuits Chapter 23. Circuit Elements and Design Circuit Diagram – a logical picture of what is...
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Transcript of Circuits Chapter 23. Circuit Elements and Design Circuit Diagram – a logical picture of what is...
Circuit Elements and Design Circuit Diagram – a logical picture
of what is connected to what in a circuit
Replace pictures of the circuit elements with symbols
Circuit Diagrams
The longer line at one end of the battery symbol represents the positive terminal
The emf is shown beside the battery Capacitance and resistance are shown beside
the symbols Wires are shown as straight line connections
between circuit elements Higher potentials are put toward the top of the
diagram
Reading Quiz 2. Which terminal of the battery has a higher potential?
A. the top terminalB. the bottom terminal
Slide 23-4
Checking Understanding
The following circuit has a battery, two capacitors and a resistor.
Which of the following circuit diagrams is the best representation of the above circuit?
Slide 23-9
The following circuit has a battery, two capacitors and a resistor.
Which of the following circuit diagrams is the best representation of the above circuit?
Slide 23-10
Answer
Kirchhoff’s Laws
Analyzing a circuit Find:
The potential difference across each circuit component
The current through each circuit component
Kichhoff’s Loop Law
To apply the loop we must identify which potential differences are negative and which are positive.
Kirchhoff’s Loop law can only be true if at least one of the potential differences ΔVi is negative
Kichhoff’s Loop Law The net change in the electric potential
around any loop or closed path must be zero
If we add all the potential differences around the loop formed by the circuit, the sum of these potential difference must be zero.
ΔVbat can be – or +
ΔVR is always – because potential across a resistor always decreases along the direction of the current
Voltage “drop” across the resistor Ohm’s law only considered magnitude of
current
The diagram below shows a segment of a circuit. What is the current in the 200 resistor?A. 0.5 AB. 1.0 AC. 1.5 AD. 2.0 AE. There is not enough information to decide.
Slide 23-13
Clicker Question
The diagram below shows a segment of a circuit. What is the current in the 200 resistor?
B. 1.0 A
Slide 23-14
Answer
The diagram below shows a circuit with two batteries and three resistors. What is the potential difference across the 200 resistor?
A. 2.0 VB. 3.0 VC. 4.5 VD. 7.5 VE. There is not enough information to decide.
Slide 23-15
Clicker Question
The diagram below shows a circuit with two batteries and three resistors. What is the potential difference across the 200 resistor?
A. 2.0 V
Slide 23-16
Answer
Series and Parallel Resistors
Two bulbs are connected in series if they are connected directly to each other with no junctions in between.
If two bulbs are connected at both ends in a circuit they are in parallel
We use equivalent resistance (the resistance of a single resistor which would replace more than one series or parallel resistors in a circuit) to solve circuit problems