need 3 experiment based on the following topics
(A) heat
(B) sound
(C) electricity
Answers
Answer:
Heat
If you go camping, you usually build a fire to sit around at night. You may make
Sʼmores, have hot chocolate and stay warm. Have you ever wondered why a marshmallow
cooks without touching the flame, why the smoke rises, or why water in a pan boils? Heat can
move from one object to another in three different ways: conduction, convection and radiation.
Conduction is the heat transfer through a substance or from a substance to another by
direct contact. Everything is made up of small particles. When the particles are moving faster,
there is more energy and the temperature is higher. As fast-moving particles touch slow-moving
particles, the energy is transferred. This causes slower particles to speed up
and the faster particles to slow down. You can demonstrate this
by rubbing your hands together very fast for 30 seconds. Now
touch them to your ears. Can you feel the heat transfer from
your hands to your ears? As your ears warm, your hands will
cool until the particles in each are moving at the same speed.
Light
Light
If you were asked to make a list of all the things that give us light, what would you write?
Light bulbs, candles or campfires may be on your list. The sun is an important source, also.
Light is energy that travels in waves and is produced by hot, energetic objects.
Light bulbs are hot, energetic objects. If
you have ever touched a lightbulb while it is on,
you know it is hot. You know the light bulb needs
energy because you have to turn the light switch
on to provide electricity for it. The electricity
flows through either a thin metal wire or a gas.
The wire or gas glows and gives off light when
Sound
If a tree falls in the forest and no one is there, does it make any sound? Sound is a form
of energy that causes particles to vibrate back and forth. How would you answer the question
about the tree falling in the forest?
When the tree hits the ground it causes the particles in the air to vibrate. Vibration is a
rapid movement back and forth. The tree creates vibrations in the air as it falls. The vibrations
spread out in all directions. If the vibrations in the air reach you, your eardrum will vibrate and
you will hear the sound of the tree falling.
Have you ever placed your hands over your ears because someone was yelling? The
loudness or intensity of a sound depends on the energy used. The more energy used, the louder
the sound. You use a lot more energy to yell than you do to whisper. The same is true with all
sounds: the more energy expended, the louder the sound.
Do you sing or play a musical instrument? If you do, you understand pitch, how high
or low a sound is. The pitch of an instrument changes by adjusting its length or width. A tromboneʼs sound changes from low to high as the slide is moved in. The pitch of musical instruments can also be changed by tightening the strings which increases the speed of vibration. The
picture below shows glasses filled with water. The glass on
the left will have the lowest pitch when tapped. It has the
greatest length of air space to vibrate, thus creating a low
sound.
To keep areas quiet, such as libraries, there are materials placed in the rooms such as carpet and upholstered
chairs to absorb noise. The absorption, the ability to take in or dampen, soaks up any noise so
people can study in quiet surroundings.