21-22 Electricity

The picture shows a lightning strike during a thunderstorm. Which statement best describes how lightning is formed?

• An electric charge builds up in a neutral cloud and is attracted to a neutral object on the ground.

• An electric charge builds up in a neutral cloud and is repelled by a neutral object on the ground.

• An electric charge builds up in a negatively charged cloud and is attracted to a positively charged object on the ground.

• An electric charge builds up in a negatively charged cloud and is attracted to a negatively charged object on the ground.

Which of these is an example of static electricity?

• A piece of metal is repelled by another piece of metal.

• A current runs through a wire and a light bulb lights up.

• A person is shocked by sticking a fork in a toaster oven.

• A person's hair stands up straight after taking off a sweater.

The picture shows a little boy that has gone down a slide. Which sentence best explains why his hair is standing up straight after going down the slide?

• His hair and the slide have like charges, making them repel each other.

• His hair and the slide have opposite charges, making them repel each other.

• The slide caused friction making each of his hairs have a like charge, which repel each other.

• The slide caused friction making each of his hairs have an opposite charge, which attract each other.

Using the stopwatch readings, which spoon melted the ice cube the fastest?

• Pure silver spoon

• Glass spoon

• Ceramic spoon

• Copper spoon

A student designs a simple circuit as shown in the diagram. What is the purpose of the switch in the student's design?

• The switch controls the brightness of the light bulb.

• The switch controls the flow of energy through the circuit.

• The switch prevents extra energy from building up in the circuit.

• The switch prevents energy from moving in the wrong direction.

Emma is moving into a new apartment. When she goes to plug in the television, she notices that the plastic coating around the power cord is damaged. The metal wires of the power cord are now exposed.

Why should Emma fix the power cord before plugging in the television?

• Electricity will not flow from the outlet to the television and it will not turn on.

• Electricity will flow from the outlet and melt the rest of the wire.

• Electricity will flow to the air instead of the television and the television could be damaged.

• Electricity could flow to Emma and be dangerous.

A student builds a battery out of a copper nail, zinc nail, wires, and a lemon. He uses this battery to light a LED light bulb. The picture shows the lemon battery he built. The student compares the light produced by the lemon to the light produced by a lamp in his room that is lit by flipping a switch on his wall.

Which statement is a correct comparison of the electricity used to power the lemon light to the electricity used to power the lamp in his room?

• The lemon light and lamp light both use current electricity to produce light, because current electricity is a continuous flow of charges that is man-made.

• The lemon light and lamp light both use static electricity to produce light, because static electricity is the release of electric charges that occurs naturally.

• The lemon light uses static electricity to produce light from a build up of charges in the lemon, but the lamp light uses current electricity to produce light from a continuous flow of charges.

• The lemon light uses current electricity to produce light from the moving electrons in the lemon, but the lamp light uses static electricity to produce light from a build up of electric charges.

Use the information and chart to answer the following question.

A student is asked to group the statements from the box on the following chart about electricity.

Which statement would be CORRECTLY classified and why?

• Negative charges moving through a wire and charging a cell phone belong under current because they do not naturally occur and are created by humans.

• A buildup of electrical charges on an object, clothes sticking together in a dryer belong under current because they have charges that move around.

• Charging a cell phone and clothes sticking together in a dryer belongs to the static side because both are temporary.

• Lightning strikes a building does not belong on either chart.

Which of these is the best description of how a bulb is lit up in a circuit?

• Electricity conducted through a wire is converted to light energy.

• Electricity is conducted from a light source to the battery.

• Electricity is overloading the battery and causing it to create light.

• Metal wires move directly from a battery to a light bulb in an open loop.

Which two objects are necessary to complete an electric circuit?

• Which two objects are necessary to complete an electric circuit?

• a power source and a light bulb

• a path for energy to flow and a switch

• a power source and a path for energy to flow