Download PHY160-4

TODAY’S OUTCOMES:
ELECTRICITY
- Review the operation of series circuits
and electric current
- Study and measure voltage and current
in electric circuits
- Construct and operate a simple battery
GRADING OF
ELECTRICAL CURRENT, PART 2
5 points:
4 - Correct outcome for each circuit in
either switch position (2 per circuit, 1
per switch position)
1 - Clear and complete expression of
ideas
14. Here are two more ways to connect the batteries, the motor, and the switch. These are not good
for much; in fact, one of them is a bad idea altogether. What do they do?
In circuit D, the motor runs normally when the switch is in the “up” position, but the
motor does not run at all when the switch is in the “down” position. The “down”
position creates a short-circuit, a potentially dangerous situation.
In circuit E, the motor again runs normally when the switch is “up”, and does not run at
all when the switch is “down”. This is because when the switch is “down”, the batteries
are arranged such that the positive ends are both adjacent. Reversing the direction of
either of the two batteries in E would result in a circuit in which the motor runs faster
when the switch is “down” than when it is “up”.
WHAT DID YOU LEARN IN THE LAST
ACTIVITY?
Take 60 seconds - each group come up
with the most important and/or interesting
thing you learned (Q.13)
WHAT YOU ARE EXPECTED TO KNOW:
- How to construct a series circuit given any
number of batteries and electrical devices
- That electric current must remain constant at
all points in a series circuit
- How placement of batteries and electrical
devices in a series circuit affects the current
BATTERIES IN SERIES: AN ANALOGY
TO SIPHONS
battery
2 1batteries
– +– +
++
– +
–
–
As you read about and measure current
and voltage in today’s activity, think
about what the proper analogies are
to these quantities in a siphon system!
One last look at a circuit studied in class
w/ water siphon analogy:
–
+
+
A
B
–
B
A
light bulb
LED
We should recall that the LED (B) was MUCH brighter than the
light bulb (A). How does the current through A compare to the
current through B?
Using a siphon analogy (right), even though we don’t know the
shape of the tube at A or B (black boxes) we know the flow rate
must be the same along the whole siphon tube, as long as the
flow rate remains constant....
The current through the the whole circuit is the same.
(Current through A = Current through B.)
TODAY’S OUTCOMES:
ELECTRICITY
- Review the operation of series circuits
and electric current ✓
- Study and measure voltage and current
in electric circuits
- Construct and operate a simple battery