4th Grade Science : Physical Science

Study concepts, example questions & explanations for 4th Grade Science

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Example Questions

Example Question #191 : 4th Grade Science

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

Possible Answers:

Conductors tell electrons what to do so they can create electricity

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

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

Conductors transmit energy so electrons can flow easily

Correct answer:

Conductors transmit energy so electrons can flow easily

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.

Example Question #7 : Observe How Energy Is Transferred By Electric Currents

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

Possible Answers:

False

True

Correct answer:

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.

Example Question #1 : Observe How Energy Is Transferred By Electric Currents

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?

Possible Answers:

A professor walking the halls with a candle

The groundskeeper throwing a broomstick

The overhead lightbulb in the greenhouse turned on

A cauldron bubbling over a fire

Correct answer:

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.

Example Question #9 : Observe How Energy Is Transferred By Electric Currents

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

Possible Answers:

False

True

Correct answer:

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.

Example Question #10 : Observe How Energy Is Transferred By Electric Currents

True or false: Electrons are negatively charged particles.

Possible Answers:

True

False

Correct answer:

True

Explanation:

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

Example Question #1 : Observe How Energy Is Transferred By Sound

Energy transferred by sound must travel through a medium. Which answer choice(s) are an example of a medium?

Possible Answers:

Gas

Liquid

All answer choices are mediums.

Solid

Correct answer:

All answer choices are mediums.

Explanation:

Sound waves must travel through a medium. This medium can be a solid, liquid, or gas. The sound waves move through each of these mediums by vibrating the molecules in the matter. Sound travels fastest through solids. Molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to move more quickly through it.

Example Question #2 : Observe How Energy Is Transferred By Sound

Sound energy decreases over distance as it is transferred through matter.

Possible Answers:

False

True

Correct answer:

True

Explanation:

Matter is made up of particles, and energy can be transferred through these particles. Sound energy decreases the further the distance required to travel. As the sound is transferred through matter, it will sound softer and more difficult to hear if the distance between speaker and listener is increased.

Example Question #2 : Observe How Energy Is Transferred By Sound

Which household item is an example of energy being transferred as sound?

Possible Answers:

A lamp

A candle

A hairbrush

An alarm clock

Correct answer:

An alarm clock

Explanation:

All of these items are household items that use or transfer different types of energy. The only object that transfers energy as sound is an alarm clock. An alarm clock is powered with electricity and then produces a sound when set to wake someone up at a particular time. Vibrations in the air create the soundwaves it provides.

Example Question #3 : Observe How Energy Is Transferred By Sound

Danthony went to a concert and heard many different bands perform. He noticed that not all singers sounded the same. Some were louder, others quieter, some had high-sounding voices, and others sounded low. What factors of sound waves affect what Danthony was hearing?

Possible Answers:

Wavelength

Amplitude

Frequency

All of the answer choices are correct.

Correct answer:

All of the answer choices are correct.

Explanation:

The reason Danthony heard so many different sounding voices at the concert was because of factors that affect sound waves. Wavelength is the measurement of a wave from crest to crest or from trough to trough. The longer the wavelength, the lower the frequency of a sound. Frequency describes how often the particles of a medium vibrate when sound waves pass through the medium. Frequency is measured in Hertz. Frequency determines the pitch of a sound. Pitch determines how we hear the sound. Amplitude is the height of a wave. It measures to the crest or trough of a wave. Amplitude determines how loud a sound is. The larger the amplitude is, the louder the sound will be.

Example Question #4 : Observe How Energy Is Transferred By Sound

What is sound?

Possible Answers:

Sound is made up of waves of electromagnetic energy.

Sound is the transfer of thermal energy.

Sound is the flow of electrons – tiny, negatively charged particles in atoms.

Sound is the movement of energy by vibrations through substances in the form of waves.

Correct answer:

Sound is the movement of energy by vibrations through substances in the form of waves.

Explanation:

When asked, "what is sound," it seems like it is a straightforward definition to explain, but there are so many layers to it that it is a complicated answer. Sound is the movement of energy by vibrations through substances in the form of waves. When a musician bangs a drum, it creates a vibration; this vibration creates sound waves that travel to our ears to be received and processed. Though the waves are invisible, they are still energy transferring information.

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