Observe how energy is transferred by electric currents

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4th Grade Science › Observe how energy is transferred by electric currents

Questions 1 - 10
1

Which object is an example of a device that converts electrical currents into heat energy?

A toaster

A freezer

The Sun

A candle

Explanation

A toaster is an example of how a device can convert electrical currents into heat energy. The toaster is plugged into the electrical outlet and electricity flows through the cord and into the heating elements of the toaster. The toaster than warms and crisps the food item placed inside. The heating coils warm the bread as a result of electrical currents being transferred.

2

Why is it important to have a good conductor when trying to transfer energy through electrical currents?

Conductors tell electrons what to do so they can create electricity

Conductors transmit energy so electrons can flow easily

Conductors block the electrons from traveling so the electricity can build-up

Conductors are not necessary when trying to transfer energy through electrical currents

Explanation

Because electricity is the flow of electrons, or negatively charged particles in atoms, conductors are necessary when trying to transfer energy through electrical currents. Conductors allow electrons to flow easily, which in turn transmits energy. Someone would not want to block electrons from traveling whatsoever when trying to create an electrical current - materials that do this would be called insulators.

3

Jamarious wants to transfer energy by electrical current for a class project. He begins observing simple household examples of electrical currents moving energy. Which answer choice is NOT an example of energy transferring through electricity?

The doorbell ringing through the house from the front porch

Lighting a candle when the power goes out to provide light

Pre-heating the oven to bake fresh cookies

Using an air conditioner to cool the house down in the summer

Explanation

All of thee examples except for one demonstrate electricity or electrical currents transferring energy in a simple household scenario. Lighting a candle when the power goes out to provide light does not use electricity or an electrical current, so it is the non-example. A candle does produce light and heat energy, but it is through a chemical reaction with the match lighting the wick. All of the other examples are creating a change using electricity.

4

True or false: Insulators assist in the transfer of energy through electrical currents.

True

False

Explanation

Insulators slow down the flow of electrons, which prevents the transfer of energy through electrical currents. For electrical currents to function correctly, the negatively charged particles must be able to flow easily. A conductor would assist in the transfer of energy through electrical currents, while insulators stop it from happening.

5

Cho wants to observe the transfer of energy through electrical currents at her school. She observes in a few of her classrooms and notices several different energy transfers. Which of the following is an example of an electrical transfer of energy?

A cauldron bubbling over a fire

A professor walking the halls with a candle

The groundskeeper throwing a broomstick

The overhead lightbulb in the greenhouse turned on

Explanation

These responses show a number of different energy transfers. A bubbling cauldron would be an example of a transfer of heat energy. A professor walking the halls with a candle is an example of light energy at work. The thrown broomstick depicts kinetic energy. The lightbulb turning on is an example of a transfer of electrical energy, because electricity causes the wire in the bulb to glow.

6

Energy cannot be transferred from place to place by electric currents.

False

True

Explanation

Energy can be moved from place to place by moving objects or through sound, light, or electric currents. Energy can also be transferred from site to site by electric currents; the currents may have been produced, to begin with by transforming the energy of motion into electrical energy. The statement presented is false because electrical currents can transfer energy.

7

Juan is trying to build a device to transfer energy through electrical currents and needs to use a conductor to allow the electrons to flow easily. Which material should he choose to use in his design?

Copper

Rubber

Wood

Plastic

Explanation

Juan should use copper if he is looking for something that is a good conductor. A conductor is a material that transmits energy. Electrons can flow easily through a conductor. If he chooses the rubber, wood, or plastic, those items are insulators and would prevent the flow of energy because electrons cannot flow easily through an insulator. Electricity is the flow of electrons – tiny negatively charged particles in atoms, so their flow mustn't be hindered.

8

True or false: Electrical and heat energy transfers follow the same process.

True

False

Explanation

Heat travels through convection, conduction, and radiation. While both heat energy transfers and electrical energy transfers require good conductors, in a heat energy transfer, the particles begin vibrating and bumping into one another more and more quickly, spreading heat. Electrical currents require electrons to travel through wires or a reaction between positive and negatively charged particles.

9

Which answer choice is an example of how electrical currents in nature transfer energy?

Lightning

Power plants

Lightbulbs

Television sets

Explanation

Lightning is a powerful example of electricity in nature. During a thunderstorm, many small bits of ice bump into each other as they move around in the air in the clouds. These collisions create an electric charge. The cloud fills up with electrical charges. The positive charges or protons form at the top of the cloud, and the negative charges or electrons form at the bottom of the cloud. The ground beneath the cloud creates a positive charge. The charge coming up from points on the ground (like treetops or buildings) eventually connects with a charge reaching down from the clouds and lightning strikes.

10

True or false: Electrons are negatively charged particles.

True

False

Explanation

Electrons are negatively charged particles, while protons are positively charged. Electrons are the primary carriers of electricity in solid objects.

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