Detecting Static Charge Using an Electroscope

Name: ______2.3 Detecting Static Charge Using an Electroscope Related Theory: A device used for detecting the presence of an electric charge is called an electroscope. In this activity, you will investigate how a metal leaf electroscope can detect the presence of a known static charge. Purpose: Write a purpose below for this lab.

Hypothesis: Write a hypothesis below for this lab.

Materials:Create a materials list below for this lab.      

Procedure:

Part A: INDUCED CHARGE SEPARATION: 1. Look at the sketch of how the leaves in the electroscope look before you do any charging. Your electroscope should look similar the one shown. Sketch the leaves and a nearby ebonite rod along with the charges on each (as shown on p. 406 of your text). Label this “DIAGRAM A” under the diagram. 2. Charge the black ebonite rod as usual and without touching it to the ball bring the rod close to the ball on the top of the electroscope and observe what happens to the leaves. Draw a sketch of the leaves while the rod is held near but not touching the ball on the electroscope. Label this “DIAGRAM B.” 3. Move the rod away and draw what happens to the leaves. Label this “DIAGRAM C.” See animation at http://www.sciencewithmrnoon.com/electroscope.swf (use your phone)

Part B: CHARGING BY CONTACT: 4. Touch the ball of the electroscope with your hand. Your electroscope should look similar to the one shown above. 5. Charge the black rod again and bring it near and then touch it to the ball on the electroscope. After touching the rod to the ball on the electroscope, move the rod away from the electroscope. Draw before (before bringing the rod towards and touching) and after (after the rod has touched and then been removed) pictures of what happens to the leaves. Label these “DIAGRAM D” and “DIAGRAM E.” 6. Touch the ball on the electroscope with your hand and get the leaves to return to normal (no charge). Part C: CHARGING BY INDUCTION: 7. Your electroscope should look similar the one shown above. 8. Have one of your partners place their finger on the ball of the electroscope. Charge the black rod as usual and without touching it to the ball, and with your partner’s fingers still on the ball, bring the rod close to the electroscope and hold it there. Observe what happens to the leaves. Draw a sketch of the leaves while the rod is held near but not touching the ball on the electroscope while the finger is touching the ball on the electroscope. Label this “DIAGRAM F.” 9. Now remove the finger from the ball. 10.Now move the rod away. Draw what the leaves look like after this procedure. Label this “DIAGRAM G.”

Observations: Record observations to show your tests and results. For each test include names of the materials used and their net charges before and after charging.

Part A: INDUCED CHARGE SEPARATION

Part B: CHARGING BY CONTACT Part C: CHARGING BY INDUCTION

Discussion Questions

1. What are three ways to produce a static charge? 2. Why were you instructed to touch the ball of the electroscope between each procedure? 3. Define induction. Explain the results of Part A. 4. What charge was left on the leaves of the electroscope in Part B? How do you know? 5. For Part C, explain why the electroscope behaved the way it did.

Write your Discussion section on a separate sheet of lined paper, stapled to this sheet. Rubric: Communication Thinking/Inquiry /4++ /4++ Criteria Level R Level 1 Level 2 Level 3 Level 4 (50-59%) (60-69%) (70-79%) (80-100%)

n  Organization of lab Not included Expresses and … with some … with … with a high o i t  Materials correct …..Or organizes ideas effectiveness considerable degree of a c

i Organization of and information effectivenes effectiveness n

u ideas is not with limited s

m evident effectiveness m o

C  Diagrams correctly Use of symbols Uses symbol and …with some … with … with a high labeled and labelling labelling with effectiveness considerable degree of  Diagrams drawn incorrect or limited effectivenes effectiveness with care absent effectiveness s

g Purpose clearly Not included Uses … with some … with … with a high n i written Or critical/creative effectiveness considerable degree of k n

i Hypothesis is logical, Demonstrates thinking effectivenes effectiveness h

T based on no processes, skills, s understanding of understanding and strategies concepts of concepts. with limited effectiveness

Reponses to questions Neutral Negative rod is A ground is attached The ground is brought near the to the sphere; this removed from the neutral sphere. This allows the electrons to sphere first then the causes an induced move off of the rod is removed. The charge separation. sphere. sphere is now positively charged.

Neutral Negative rod is A ground is attached The ground is brought near the to the sphere; this removed from the neutral sphere. This allows the electrons to sphere first then the causes an induced move off of the rod is removed. The charge separation. sphere. sphere is now positively charged.