Day 2: Batteries12.3Name ______
1)Make a simulated circuit with one battery and bulb using Add a second battery.
Join the batteries so they point the same way.
a)Compared to the brightness with just one battery, the bulb will be
A)brighterB) dimmer C) the sameD) unlit
Observe and Explain: A)The real circuit is clearly brighter and the simulation helps to visualize what we think is happening.Each battery is pushes electrons in the same direction, so there is a harder push.
Join the batteries so they are opposite.
b)Compared to the brightness with just one battery, the bulb will be
B)brighterB) dimmer C) the sameD) unlit
Observe andExplain:D) One battery pushes and the other pulls. They will mostly cancel and any difference will not be enough to light the bulb.
c)Youhave observed the effects qualitativelyand now you will add quantitative observations using a voltmeter. Measure the voltage across the bulb in each situation.
One battery: ______Two batteries (same)______Two batteries (opposite) ____
Simulation: One battery (9 V), 2 in series same direction (18 V), 2 series opposite direction (0 V). Real: One battery (~1.5 V), 2 in series same direction (~ 3 V), 2 series opposite direction (~ 0 V). Note: We are informally introducing voltage. Don’t bother with a volt is a J/C etc.
2)You will make a real circuit with one motor and one, two, three and then four batteries.The batteries will be connected one after the other in the same direction.
a) Predict what the voltage will be across the motor each time. Observe and record the voltage.
Number of batteries / Prediction (V) / Observation (V)1 / 1.5 / Slightly smaller than 1.5 V
2 / 3 / Slightly smaller than 3 V
3 / 4.5 / Slightly smaller than 4.5V
4 / 6 / Slightly smaller than 6 V
The alligator clips use up some of the voltage, batteries may not be 1.5 V if old.
b) Graph your results below.
c) Draw a straight line that passes through (0,0) and as close to the data points as possible. Why did the points not all lie exactly on the line?
The batteries are not all 1.5 V.
d)Calculate the slope of the line (rise/run). What does this represent?
It is the average voltage per battery. It should be around but less than 1.5 V.
3)You have a collection of different batteries. Name them and measure their voltages.
D1.5 VC1.5 VAA1.5 V AAA1.5 V9-V9-V
4)Describe how to make a rectangular 9-V battery from the cells above. Draw a diagram.
The battery is made from six AAA cells in series. Show them a dissected battery.
5)What is the difference between a battery and an electriccell?
The terms are usually used interchangeably. Strictly speaking, a battery is two or more cells connected together. Only the 9-V is a battery of cells.
6)The differences between batteries can be understood using leaky water bottles as a model.
a)Draw what the water flow will looks like in each of the examples above. Show more flow (current) with a thicker line and more energy (voltage) with a line that shoots further. Demonstrate and compare with predictions. The bigger holes can support more’ current’ and the higher holes provide more ‘voltage’.
b)Some batteries provide more voltage. Which illustrates this? A: The bottom has greater pressure
c)Some loads draw more current. Which illustrates this? B and C: The left has more flow.
d)Some batteries will last longer. Which illustrates this? C: Has more water stored than A or B.
The difference between V and I is hard to understand. This is one of many models that can be used. At this point we just want students to get a feel that voltage is something like pressure that pushes the charges and that electric current is like water current, i.e. rate of flow, amount/time
Textbook Reinforcement: Read pages 511 to 514 and answer question 4, 5 and 6.