Datasheet-2

Project 20:
What voltage did you measure in Part A?
Approximately 4.5V.
What voltage did you measure in Part B?
Approximately 3V.
What voltage did you measure in Part C?
Approximately 1.5V.
Project 21:
Does the lamp brightness change like the voltage does
(are they proportional)?
Yes and they are proportional.
Project 22:
Does the motor speed change like the voltage does (are
they proportional)?
Yes, and it is proportional.
Project 23:
Does the LED brightness change like the voltage does
(are they proportional)?
No, the brightness is not proportional.
Project 24:
With both lamps on, what is the voltage measured
across the top lamp?
Half the battery voltage, Approximately 2.25V.
With both lamps on, what do you think the voltage
across the bottom lamp is? Swap the locations of the
meter and press switch to see if you are right, then
swap them back.
Same as the top.
With the press switch pushed, what is the voltage
measured across the top lamp?
The battery voltage, approximately 4.5V.
Is it double the voltage measured across the top
lamp when both lamps were on?
Yes
Why did the voltage change?
The S2 shorts the bottom lamp so all the voltage is
across the top lamp
Is the top lamp brighter now?
Yes
Project 25:
With all three lamps on (both switches off), what is
the voltage measured across the top lamp?
Approximately 1.5V.
With all lamps on, what do you think the voltage
across each other lamp is? Swap the location of the
meter with either switch to see if you are right, then
swap them back.
Approximately 1.5V.
Turn on one or both switches, and compare the volt-
age measured with one, two, or all three lamps on.
The voltage increases to 3V with one lamp off and
4.5V with two lamps off.
Why did the voltage change?
The voltage divides evenly, because the lamps all
have the same characteristics and in series.
Project 26:
With all three lamps on (both switches off), what is
the current?
Approximately 200mA.
Turn on one or both switches, and compare the cur-
rent measured with one, two, or all three lamps on.
The current should be higher.
Why did the current change?
Turning a switch on shorts the lamp, decreasing the
circuit’s resistance. The lower the resistance, the
higher the current.
Project 27:
Are the currents through circuit branches B, C, and
D the same or different?
The currents should be the same.
Add up the currents through circuit branches B, C,
and D. How does the total compare to the main cir-
cuit current (part A)?
The total current through circuit branches B, C, and
D should be the same as the main circuit current.
Project 29:
Are the three switches connected in series or in par-
allel?
The three switches are connected in series.
Give an example of an AND circuit in your home.
Fuse box switch and wall switch controlling a lamp.
Project 30:
Are the three switches connected in series or in par-
allel?
The three switches are connected in parallel.
Give an example of an OR circuit in your home.
Several sensors controlling an alarm system.
Project 31:
How much brighter is the right lamp compared to the
others?
The right lamp is typically 80% brighter
Why do the two lamps on the left turn on slowly?
Because less current flows through them.
Project 32:
What is the voltage across the top lamp?
Half the battery voltage, approximately 2.25V.
What is the voltage across the lower lamps?
Half the battery voltage, approximately 2.25V.
Remove the top 3-snap wire (which connects to the
battery holder) and place the meter there. Set the
meter to the 1A setting and measure the circuit cur-
rent.
Approximately 250mA.
Find a fluorescent or LED bulb and feel the heat coming
off it; you won’t feel much. Find an incandescent lamp
THAT HAS BEEN OFF FOR A WHILE and turn it on.
Feel the heat it produces; it soon becomes too hot to
touch. How much hotter is the incandescent bulb?
Incandescent bulbs are a lot hotter because most
of their energy is being released as heat, not light.