Electroscope
Purpose:
Electroscopes were used in the early detection of radiation. Original work dealt with cosmic rays. We will use the one you make to detect alpha or beta particles. You may also have used an electroscope for static electricity experiments. Electroscopes work because two objects with the same electrical charge repel each other which in this case is aluminium foil.
Materials:
- stick of gum
- bottle
- anhydrous salt
- large paper clip
- watch
- some type of stopper (styrofoam, rubber, cork...)
- glue
- comb
Directions:
- Cut the gum wrapper that has aluminium foil so it measures 1 cm X 7.5 cm. Put notches in the middle of the aluminium foil.
- Put this wrapper from a stick of gum into water to separate the foil from the paper. Then allow the foil to dry. HANDLE CAREFULLY.
- Straighten out the paper clip. Put a 90 degree bend in the paper clip about 1 cm from the end. Push the other end through the stopper and bend it over on itself so the wire cannot fall through the stopper.
- Place the aluminium foil on the 90 degree bend of the wire and glue it in place. Be sure the foil touches the wire when the glue is dry.
- Cover the bottom of the bottle with a thin layer of anhydrous salt.
- Place the aluminium foil leaves about 2 cm above the bottom of the bottle and wait ten minutes to allow the salt to absorb the water from the air in the bottle.
Procedure:
- Have someone comb their hair and then touch the wire loop on top of the electroscope. You can also rub wool and charge a record or some other material. The leaves should stand out. Record how long it takes in seconds for the leaves to come back together.
Do this two or more times and then figure out the average time it takes for the electroscope to lose it's charge.
- Using an alpha ray source (Coleman lantern mantle) repeat proceedure 1. You can also try a watch or old clock with a radium dial.
- What happens when you charge the electroscope with static electricity and then bring the alpha source to the top loop?
Discussion:
Does your experiment show that rays produce ions? Why or why not.
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Electroscopes were used in the early detection of radiation. Original work dealt with cosmic rays. We will use the one you make to detect alpha or beta particles. You may also have used an electroscope for static electricity experiments. Electroscopes work because two objects with the same electrical charge repel each other which in this case is aluminium foil.
- Cut the gum wrapper that has aluminium foil so it measures 1 cm X 7.5 cm. Put notches in the middle of the aluminium foil.
- Put this wrapper from a stick of gum into water to separate the foil from the paper. Then allow the foil to dry. HANDLE CAREFULLY.
- Straighten out the paper clip. Put a 90 degree bend in the paper clip about 1 cm from the end. Push the other end through the stopper and bend it over on itself so the wire cannot fall through the stopper.
- Place the aluminium foil on the 90 degree bend of the wire and glue it in place. Be sure the foil touches the wire when the glue is dry.
- Cover the bottom of the bottle with a thin layer of anhydrous salt.
- Place the aluminium foil leaves about 2 cm above the bottom of the bottle and wait ten minutes to allow the salt to absorb the water from the air in the bottle.
- Have someone comb their hair and then touch the wire loop on top of the electroscope. You can also rub wool and charge a record or some other material. The leaves should stand out. Record how long it takes in seconds for the leaves to come back together.
Do this two or more times and then figure out the average time it takes for the electroscope to lose it's charge.
- Using an alpha ray source (Coleman lantern mantle) repeat proceedure 1. You can also try a watch or old clock with a radium dial.
- What happens when you charge the electroscope with static electricity and then bring the alpha source to the top loop?