Worksheet

Launch Day Fields: A Magnet Switch and a Foil-Leaf Jar

Grade 8 fields practice: a rocket club tests a magnet switch through tube walls and a charged parachute near a foil-leaf jar.

Grade 8ScienceInteractive · Printable

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1 NGSS standard
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11 questions
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Details

Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Circle the answer, Short answer

About this worksheet

What students practice

Students use investigation data to show that magnetic and electric fields act on objects without touching them.
Students evaluate how a test was designed and what a shielding test shows about two kinds of fields.

How to use

Read the launch notes together and name the variables in each investigation before students answer; a real magnet and a rubbed plastic bag make a quick demo.

Curriculum

NGSS standard covered

MS-PS2-5

Investigate how fields let objects exert electric and magnetic forces on each other without touching.

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Name Date

Launch Day Fields: A Magnet Switch and a Foil-Leaf Jar

Investigate forces that act across a gap and through walls.

Investigation 1: The magnet switch

Read the club's notes and Table 1, then answer the questions.

Launch Notes: Two Fields Before Liftoff

1The Sandhill Rocketry Club meets on a mowed field outside town for its spring launch day. This year the club's biggest rocket carries a small altimeter, a device that records how high the rocket flies. The altimeter sits sealed inside the body tube, with no hole for a switch. Instead, it has a magnetic switch: when someone holds a small magnet against the outside of the tube, the switch inside closes and the altimeter's light blinks on. With no magnet nearby, the light stays off.

2Eighth grader Leocadia Petrov wanted to know how far the switch's magnet could reach and whether the tube's material mattered. She set the switch on a block and slid the magnet toward it along a ruler, three times for each setup, writing down the distance at which the light first came on. She tested the switch with only air in between and with flat wall pieces between the magnet and the switch: cardboard, fiberglass, aluminum and steel. Every wall piece was 1 mm thick.

3On launch morning the air was cold and very dry. When Tobiah Rinaldi unfolded the rocket's thin plastic parachute, it crackled, clung to his sleeve, and bits of dry grass jumped up onto it. Club advisor Mr. Cornelius Abara helped him build a foil-leaf jar: a paper clip pushed through the jar's cardboard lid, with two thin strips of aluminum foil hanging side by side from its hook inside. When a charged object comes near the top of the clip, the two foil leaves swing apart, even if nothing touches the clip.

4Before each reading, Tobiah rubbed the parachute 10 times with a wool scarf. Then he held it still at a measured height above the clip and read the gap between the tips of the foil leaves (Table 2). He also held a parachute that had not been rubbed 2 cm above the clip.

5Last, Tobiah set the whole jar inside a cardboard box and held the rubbed parachute 5 cm above the box: the leaves spread to 18 mm. He lined the inside of the box with aluminum foil on every side, leaving only a pencil-sized peephole to look through, and tried again. This time the leaves did not move. When he lifted the jar out of the foil box, the same parachute at 5 cm spread the leaves to 18 mm again. Mr. Abara then set a compass inside the foil-lined box, which sat still on the table, and watched it through the peephole. As he brought the switch magnet near the outside of the box, the needle turned toward it.

Table 1: Farthest Distance That Turned the Altimeter On
Material in the gap	Trial 1 (mm)	Trial 2 (mm)	Trial 3 (mm)	Average (mm)
Air only	24	26	25	25
Cardboard, 1 mm	25	24	26	25
Fiberglass, 1 mm	26	25	24	25
Aluminum, 1 mm	24	25	26	25
Steel, 1 mm	5	6	7	?

Which result is the best evidence that the magnet acts on the switch without touching it?

A. The light came on with the magnet 25 mm away, and it stays off with no magnet.
B. The altimeter sits sealed inside the body tube, with no hole for a switch.
C. Leocadia slid the magnet toward the switch along a ruler three times for each setup.
D. Leocadia tested five setups, using wall pieces that were 1 mm thick.

Find the missing value in Table 1.

The average distance with the steel piece between the magnet and the switch was mm.

What does Table 1 show about the magnet's field and the wall materials?

A. The field passed through cardboard, fiberglass and aluminum as easily as air, but steel weakened it.
B. Metal pieces blocked the field, since the light needed the magnet much closer with aluminum and steel.
C. Thicker pieces weakened the field more, since the steel piece was much thicker than the cardboard piece.
D. Fiberglass made the field stronger, so the light came on farther away with fiberglass than with air.

Why did Leocadia make every wall piece 1 mm thick?

A. So that the magnet would not get weaker over the course of the test
B. So that a change in distance comes from the material, not from a thicker wall
C. So that the switch would close at the same distance for each of the four materials
D. So that the steel piece would weigh the same as the cardboard piece

Suppose the club built body tubes from each material in Table 1, each with a 1 mm wall. The switch sits 12 mm from the magnet when the magnet is held against the outside of the tube. Circle every tube material that would let the magnet turn the altimeter on.

CardboardFiberglassAluminumSteel

Investigation 2: The parachute and the foil-leaf jar

Use paragraphs 3 to 5 and Table 2 to answer the questions.

Table 2: Rubbed Parachute Above the Foil-Leaf Jar
Height above clip (cm)	Leaf gap (mm)
2	30
5	18
10	8
20	3
40	0

Use Table 2. Compare the leaf gap with the parachute 2 cm above the clip and 20 cm above the clip.

The gap at 2 cm was times the gap at 20 cm.

Which statement best describes the pattern in Table 2?

A. The gap shrank by about 6 mm for each 5 cm the parachute moved away.
B. The gap shrank as the parachute moved away, and it fell fastest close to the clip.
C. The gap grew as the parachute moved away, since the field spreads out wider.
D. The gap stayed near 30 mm until the parachute was raised to 20 cm above the clip.

Why did Tobiah also hold a parachute that had not been rubbed 2 cm above the clip? (With it, the leaves did not move.)

A. To show that the wool scarf moves the leaves when it is held close to the clip
B. To show that a parachute held 2 cm away is too far from the clip to move the foil leaves
C. To show that air pushed by his hand is what made the foil leaves swing apart
D. To show that the charge from rubbing, not the parachute being close, moved the leaves

Use paragraph 4. Why did Tobiah rub the parachute 10 times before every reading?

A. So the parachute would get warmer and pull harder on the paper clip
B. So the leaves would spread to the same gap at every height
C. So the charge stayed about the same and only the height changed
D. So the parachute would fold up small enough to hold still

10.

Use paragraph 5. Which conclusion fits all of the box tests best?

A. The foil lining blocked both fields, and the compass turned because the box was bumped as the magnet came near.
B. The foil kept the parachute's electric field from the leaves, but the magnet's field still reached the compass.
C. The cardboard box blocked the electric field, and the foil then added a second field of its own.
D. The parachute lost its charge during the foil test, which is why the leaves stayed still that time.

11.

Leocadia's launch report says: "Both of our investigations show that objects can push or pull on each other through fields, without touching." Do you agree? Write a claim, give evidence from Table 1, Table 2 and the box tests, and explain your reasoning. Include what the foil-lined box shows about the two kinds of fields.