7 junio, 2024

10 science experiments for high school: physics, chemistry, biology

Today I bring you a list of high school science experiments with which you can learn concepts of physics, chemistry and biology. Do scientific experiments means visualizing phenomena and corroborating theories; they also represent an opportunity to become familiar with the scientific method.

All experiments are easy to perform and use everyday equipment and materials. For the interpretation of the results, at least a high school student level is required.

1- Construction of a homemade electromagnet

Materials

-1.5V alkaline batteries (2 or 3 batteries)

-Battery holder

-Thin and enameled (varnished) copper wire for windings.

-Steel screws.

-Iron nails.

Procedure

-Wind the enameled copper cable around one of the steel screws.

-With a cutter or a knife, scrape the varnish off the free ends of the copper cable that was wound on the steel screw.

-Place the batteries in the battery holder and connect the ends to the terminals of the battery holder.

Experiment

-Approach the tip of the screw to the nails and observe that they are attracted.

-Note that when disconnecting the winding cable the electromagnet stops working.

-Increase the power of the magnet by connecting more batteries in series.

-Increase the magnetic field of the electromagnet by placing more winding turns.

Points to check

-The magnetic force is greater with more current.

-With the same current the magnetic force increases if the number of turns increases.

-With the same number of turns (each turn is a turn) and current, the power of the electromagnet increases if the turns are tightened or approach each other.

-If the screw is unscrewed and the spiral is left alone, the magnetic effect continues but is substantially weakened.

2- Convection current

Materials:

A sheet of paper
a piece of thread
A candle
Lighter

Procedure

-On the sheet of paper draw a spiral.

-Cut and make a hole in the center of the spiral.

-Pass the piece of thread through the spiral. Tie a knot at the end of the thread so that it does not slip out of the coil.

-Raise the spiral with the thread, in such a way that a helicoid is formed.

Experiment

-Turn on the candle.

-Place the paper spiral already suspended by the thread, on the lit candle.

Caution: heThe paper coil should be away from the flame, so that it does not ignite.

Points to check

-Note that the helicoid begins to rotate. The reason is the updraft of hot air. Warm air rises because it is lighter than cold air.

-Increase the turning speed by placing two sails instead of one.

3- Refraction of light

Materials

-A glass cup

-A jug with water

-A coin

-A pencil

Procedure

-Place the coin on the table.

-Then put the glass cup on the coin.

experiment A

-Look at the coin under the glass, from an oblique position and from above.

Now pour water into the glass and repeat the observation from a side angle and from above.

Points to check

-When the glass is empty, the coin can be seen through the glass both from the side and from above. But if the glass is filled with water while we look at the coin from a 45º angle, we notice that it suddenly disappears from our sight.

-If we look directly from above we notice that the coin is still there. The phenomenon is explained because light bends when it passes from one medium to another.

-When the water is added at the interface between the glass and the water, a deviation of the grazing light is produced at the bottom of the glass and therefore the coin is not visualized.

experiment B

-Now place the pencil in the glass with water in such a way that one part is submerged and the other is in the air.

Points to check

-Look at the pencil from the side: it seems to have broken. Once again, the explanation for this phenomenon is the deviation that a light ray suffers when it passes from one medium to another.

4- See the germs in the mouth with a homemade microscope

Materials:

A couple of glasses or cups
A syringe without the needle
a sewing needle
a laser pointer
Scotch tape

Procedure

-Fill the syringe with water.

-We support the wings of the syringe on the walls of the two vessels that will act as columns and support for the syringe.

-Squeeze the syringe gently until a drop forms at the tip that is held by surface tension to the edges of the syringe tip.

-Pass the adhesive tape around the laser button so that it stays on.

-Point the laser light at the drop and see the projection on the wall.

Experiment

-Rub the sewing needle carefully, without prickingby the inner wall of the mouth.

-Touch with the tip of the needle previously rubbed in the mouth, the drop of water at the tip of the syringe.

-Observe the projection and notice the differences.

Points to check

-In the projection of the laser light on the wall, the germs in the mouth are amplified.

-You can repeat the experiment, using for the syringe water from a vase, which may contain microorganisms such as paramecium and amoeba.

5- Lemon battery

Materials

-Lemons

-Copper coins, or bare copper wire.

-Galvanized screws

-Voltmeter

-Cables

-Alligator type cable clips

Procedure

-A lemon is taken and a piggy-style slot is made in it to insert the copper coin.

-The galvanized screw is screwed to the opposite side and inserted.

-The alligator clips are adapted and connected to the voltmeter leads.

-The positive alligator is connected to the copper coin.

-The negative alligator of the voltmeter is connected to the galvanized screw.

Points to check

-Measure the voltage produced by the lemon battery. This voltage should be a little less than one volt.

-Build a second and third lemon cell, connect in series and check the voltage.

-Try lighting a flashlight bulb. Try one or multiple lemon batteries in series.

-Now connect the lemon batteries in parallel. Check the voltage.

-Apply the parallel combination of lemon batteries to the flashlight bulb.

-Draw your conclusions.

6- Homemade pH indicator

Materials:

-Glass containers

-Distilled water

-Purple cabbage

-Filter paper

-Cooking pot

-Kitchen

-Glass container

Procedure

-Chop purple cabbage.

-Cook the cabbage pieces in a pot for 10 minutes.

-Remove from the stove and let sit until cool.

-Strain or filter into a clean container, preferably glass.

-Save the liquid extracted from the purple cabbage, which will serve as a pH indicator.

Points to check

-The pH indicator works like this:

i) For an acidic substance it turns from pink to red.

ii) If it is a neutral substance, it maintains its dark blue color.

iii) When tested in alkaline or basic substance, it turns green.

try different substances

-Acids that are safe to handle: vinegar and lemon juice.

-Cola soda

-Tomato

-Human urine

-Pure water

-Saliva

-Salt water or sea water

-Sodium bicarbonate.

-Toothpaste

-Milk of magnesia

-Homemade bleach or ammonia (use plastic gloves, do not touch with your hands or clothing)

-To carry out the tests it is useful to make strips of absorbent paper that are impregnated with the pH indicator.

-Write down in a notebook, classify in descending order, from the most acidic substance to the most alkaline.

Caution

Very strong acids and bases can cause burns and irritation to the skin, mucous membranes and eyes. It is convenient to wear plastic gloves throughout the experiment, especially if you have sensitive skin.

7- Extraction and observation of DNA

Materials

-Chicken livers

-Liquid dishwashing detergent

-Meat tenderizing enzymes, such as papaya juice or powdered meat tenderizer.

-Ethyl alcohol without coloring

-Blender

-Glass bottle

-Fine strainer

-Beaker with graduations

-Elongated glass container or test tube.

Procedure

-Place raw chicken liver in the blender glass.

-Add a little water and blend until a creamy paste is obtained.

-Pour the liquefied liver through a strainer into the beaker with graduations.

-Measure the amount of liquid in the container.

-Dishwasher is poured, in a measure equal to a quarter of a measure of the liver liquid.

– Stir with a spoon.

-Add a tablespoon of meat tenderizing enzymes or papaya juice and stir for five minutes.

-Stir gently, so that the DNA chains are not broken.

-The mixture is poured into an elongated glass test tube type container.

-Tilt the test tube and carefully pour the alcohol in such a way that it does not mix with the bottom liquid.

Points to check

-After a few minutes, you can see some white filaments inside the alcohol, coming from the mixture of liver, detergent and enzymes. Those filaments are the DNA of the chicken.

9- Homemade capacitor (Leyden bottle)

Materials

-Glass or plastic jar, such as mayonnaise.

-Perforated plastic insulating cover through which a rigid wire or cable will be passed.

-Rectangular strips of kitchen aluminum foil to cover, glue or adhere the outside and inside of the jar.

-A flexible cable without insulation that is attached to the inside of the rod so that it makes contact with the aluminum foil that covers the interior wall of the bottle

-It is important that the aluminum coverage does not reach the edge of the jar, it can be a little more than half.

– Cable without insulation that will be linked to the outer aluminum sheet.

Note: Another version that avoids the work of placing the aluminum foil inside, consists of filling the bottle or jar with a solution of water and salt. which will act as an interior plate.

Procedure

-If you have an old television or monitor, whose screen is cathode ray, you can use it to charge the bottle.

-Hold the bottle with one hand by the outer plate, while approaching and touching the screen with the cable that connects to the inner part.

-Then take the cable attached to the external part and bring it closer to the cable that comes from the internal part of the bottle.

Points to check

-Observe that when the cable connected to the outside is brought closer to the one that comes from the inside, a spark is produced, showing that the bottle has been electrically charged.

alternative procedure

-In case you do not have a suitable screen, you can charge the Leyden bottle by bringing it closer to a woolen cloth that you have taken from the clothes dryer.

-Another option for the charging source is to take a piece of plastic tube (PVC) that has previously been sanded to remove the varnish. Rub the tube with a paper towel until the tube is sufficiently charged.

10- Newton’s second law

Materials

-Elevator

-Scale or bathroom weight

-Notebook

Procedure

-Take a bathroom weight to an elevator, place yourself on it and record the values ​​it marks during the start of ascent, the start of descent and during the period that it moves at constant speed.

Points to check

-Now apply Newton’s second law, for it dDraw a force diagram and find the acceleration of the elevator.

-Calculate the accelerations of the elevator corresponding to each case.

References

Easy Science. Pile of…

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