COGNIA_PARCIAL QUÍMICA_1°

Juan and Rob investigate electrically charged balloons. They each blow up a balloon and tie a knot at the open end. They each tie a long piece of string to the knot of their balloon so that they can hang the balloons near each other. The chart shows two tests and the results. Static Electricity Investigation Test 1 2 DescriptionResult Juan Balloon 1 Rob Balloon 2 Balloon 1Balloon 2 Balloon 1Balloon 2 Juan Balloon 1 Balloon 2 was not rubbed on a head. Which question can be answered by this investigation?

• How long does a balloon keep an electrical charge?

• What is the effect of a string tied to a balloon on the electrical charge?

• What is the effect of an electrically charged balloon on another balloon?

• Are some kinds of balloons easier to electrically charge than other kinds of balloons?

Eva does an investigation using an electrically charged glass rod to pick up small pieces of paper. She electrically charges the glass rod by rubbing it with a wool cloth. For each test, she rubs the glass rod a different number of seconds before picking up pieces of paper. The data from the investigation are shown in the table. Data for Glass Rod Investigation Test 1 2 3 4 5 Number of Pieces of Paper Picked Up 2 3 5 7 8 Number of Seconds Glass Rod is Rubbed 5 10 15 20 25 Which question can be answered by this investigation?

• What effect does the wool cloth have on the pieces of paper?

• What effect does the amount of time spent rubbing the glass rod have on the electrical charge on it?

• What effect does the kind of material used for rubbing have on the electrical charge on the glass rod?

• What effect does the size of the pieces of paper have on the number of pieces that can be picked up?

Harry is investigating magnets. He hangs a bar magnet from a string so that the magnet can turn in any direction. Harry places a second bar magnet on a table. His setup is shown. Harry slowly moves the hanging magnet closer to the magnet on the table.

a. Write a question about the way magnets behave that can be answered by this investigation.

b. WHAT WILL HAPPEN TO THE MAGNETS IN THE IMAGE, OR IF I PUT TWO IDENTICAL IMAGES TOGETHER?

Ana and Ben are investigating static electricity. Ana and Ben each rub a balloon against wool to make static electricity on the balloons. Then, they each hold their balloon near the top of their head.

a. Write a question about static electricity that can be answered by this investigation. The balloon Ana is holding causes her hair to stand straight up. The balloon Ben is holding causes his hair to move up only a little bit. Ana and Ben wonder why the results are different.

b. Identify two things in the investigation that may have had an effect on how much their hair moves.

In an electromagnet, wire is wrapped around an iron nail and then attached to one or more batteries to make an electrical circuit. A magnetic force is created as electricity flows through the circuit. Jack makes the two electromagnets shown. Jack uses some steel safety pins to test the electromagnets.

a. Write a question that can be tested to find the effect that an electromagnet has on a steel safety pin.

b. Write a question that can be tested to find the effect of having two batteries instead of one

battery in an electromagnet.

Claire does an investigation with a magnet and five metal paper clips. She slowly brings the magnet closer to the paper clips, as shown. Write two questions about the effect the magnet has on the paper clips that can be answered by this investigation.