Induction and Grounding
Charge separation, grounding, and charging conductors without contact
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Induction
Try this at home! Charged comb attracting a coke can
Show Me The Physics
School blocks YouTube?
Grounded, neutral objects
Case III - Negative rod/neutral object
Electrons are repelled down into the ground. Object becomes positive
Case IV - Positive rod / neutral object
Neutral object becomes negative as electrons are drawn up from the ground
Case V – Induction w/ grounded electroscope
Show Me The Physics
1. A negative rod is brought near, 2. A negative rod is brought near,
Electroscope grounded
When Ground
Removed,
Electroscope Charge?
Positive
Electrons left Electroscope
Negative
Established 1995 Use any material on this site (w/ attribution) |
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Check Your Understanding
5 quick questions — pick an answer to see if you’re right.
1. A negative rod is held near a grounded neutral object. What happens?
2. A positive rod is held near a grounded neutral object. What charge does the object get?
3. Compared with the charging rod, induction with grounding gives an object
4. Negative rod near an electroscope, top touched with a finger, rod removed, then finger removed. Final charge?
5. A charged comb pulls an empty, neutral soda can toward it without touching. Why?
Grounding a Fuel Truck
As a fuel truck drives, friction with the air and road can build up charge on the truck. Before unloading fuel, the driver connects a grounding cable from the truck to a metal rod in the Earth.
Why is the truck grounded before fuel is unloaded?
▶ Want a challenge? Open 6 more Regents-style questions (harder · mixed formats)
Challenge score: 0 / 6
C1. Place a check mark in three boxes to indicate the design choices that would make the truck’s grounding system safer.
C2. If the truck is negatively charged, what happens when it is grounded?
C3. A driver makes the following claim.
Place a check mark in either the Support or Refute box. Justify your response.
C4. Before grounding, the truck has a charge of −2.4 × 10−6 C. Substitute numerical values into a mathematical representation that can be used to determine the number of electrons that flow into Earth when the truck is grounded. Then calculate the number of electrons.
C5. An electronics technician wears a wrist strap connected to ground. What is its purpose?
C6. The truck rides on rubber tires. Explain why the tires allow charge to build up on the truck while it drives. Then a company proposes adding a conductive strap that drags on the road at all times. Identify one benefit and one drawback of this design.