Positive Conduction | Show Me The Physics

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Conduction
Postitive Rod

Positive Conduction lesson illustration

If the balloon is negatively charged,
what is the charge of the cat?

Staticy Cat vs. Balloon

Conduction Positive Rod

Positive Conduction lesson illustration

Conduction, Induction

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Conduction
Fill in the Blank Notes

Conduction with a Positive Rod

Positive Conduction lesson illustration

Frame 1 - Neutral Electroscope

Positive Conduction lesson illustration

Frame 2 - Contact - Positive Rod

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Frame 3 - Charge Acquired?

What will the electroscope look like after the
positive rod is removed?

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Electroscope loses electrons

Charge?

Positive

Check Your Understanding

5 quick questions — pick an answer to see if you’re right.

1. A positively charged rod touches a neutral electroscope. What does the electroscope do?

2. After touching a positive rod, what is the electroscope's charge?

3. What do the electroscope leaves look like after the positive rod is removed?

4. A balloon rubbed on a cat becomes negative. What is the cat's charge?

5. A student says a positive rod gives protons to the electroscope. What's wrong?

NYSSLS Regents Practice · Electricity · Positive Conduction

Touching With a Positive Rod

A glass rod rubbed with silk becomes positively charged. A student touches the rod to a neutral metal sphere on an insulating stand, then removes the rod.

Which statement correctly describes what happens to the sphere?

▶ Want a challenge? Open 6 more Regents-style questions (harder · mixed formats)

Challenge score: 0 / 6

Support or Refute · Justify

C1. A student makes the following claim.

Claim: The mass of the metal sphere decreased very slightly when it became positively charged.

Place a check mark in either the Support or Refute box. Justify your response using a particle model of charge transfer.

Support Refute

Multiple choice

C2. Two identical spheres with charges +8.0 nC and −2.0 nC touch and separate. What is the charge on each?

Substitute values

C3. After the rod is removed, the sphere has a charge of +6.4 × 10⁻⁹ C. Substitute numerical values into a mathematical representation that can be used to determine the number of electrons the sphere lost. Then calculate the number of electrons.

n = ( × 10⁻⁹ C)( × 10⁻¹⁹ C) = × 10¹⁰ electrons

Select all that apply

C4. Place a check mark in three boxes to indicate the statements that are true after the rod has touched the sphere and been removed.

Protons moved from the rod onto the sphere. The sphere has fewer electrons than protons. The total charge of the rod–sphere system increased. The rod is still positive, but with a smaller charge than before. The sphere and the rod have charges of the same sign. The sphere gained electrons from the rod.

Multiple choice

C5. Which charge could not be found on an object?

Constructed response

C6. The student can hold the glass rod in her hand while she rubs it and it stays charged. When she tries the same thing with a metal rod held in her bare hand, the metal rod does not stay charged. Explain this difference in terms of how charge moves in each material.

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