A Personal Alarm System

Lets make an alarm to prevent an authorised entry into the room!

Materials Required

• 9-Volt Battery with a battery clip
• An electricity conducting paper clip
• A small bulb and a bulb socket
• 2 Upholstery Tacks
• Tape
• Scissors & Hammer
• Wire with stripped ends
• A spool of thread

Instructions

1. Hammer the tacks into the wall close to the door, make sure the lower tack is a closer to the upper one relatively but the perpendicular distance between the two must be close. (See Picture)



Use Picture for Reference. Picture NOT TO SCALE

2. Push the bulb firmly into the socket and attach the battery clip to the 9-Volt battery. Twist the red battery together with one of the light socket wires. Twist the black battery clip wire tightly around the bottom tack. Twist the remaining light socket wire tightly around the top tack. Tape the wires to the wall as shown.

1. Securely tape a paper clip to the opposite door frame. Place the spool of thread on the floor. Poke the thread through the paper clip. Pull the thread across the closed door, towards the tacks
2. Tie one end of the thread to the other paper clip. Poke the paper clip under the black battery clip wire. Let it hang down so it doesn't touch the bottom tack as long the door is closed.

What Happens???

When the door is pulled the paper clip is pulled to the bottom tack causing the circuit to be completed, and hence the electricity flows causing the light to glow.

HOW TO USE A WATCH FOR A COMPASS?

Need a compass immediately? Don't have it with you right now? Don't worry... use your wristwatch!

Materials Required:
1. Analog Watch
2. A sunny day

Instructions

• Stand outdoors. Take the watch in your palm and point the hour hand towards the sun. If it is before noon, travel clockwise around the watch face from the hour hand to the number 12. Imagine a line that goes from the centre  of the watch halfway between the hour hand and 12. The line is pointing South, the opposite is north.
• After noon, travel counterclockwise from the hour hand to 12 and then divide the angle into half. The halfway point is south.
• At noon, the 12 will point towards south.

Hope this helps ;)

DISPLACEMENT REACTION....... WHAT IS IT? HOW IS IT DONE? EVERYTHING YOU NEED TO KNOW

This experiment focuses on "Displacement Reaction" for high school students.

Displacement Reaction: A reaction in which a more reactive element displaces or takes place of an element with lower reactivity

Materials:

1) Three Iron nails

2) Sand paper

3) 2 test tubes

4) Copper Sulphate Solution (CuSO₄) 

5) Thread

6) Test tube stand

Instructions

• Take 2 test tubes and put 10 ml copper sulphate solution in each.
• Put the first test tube on the stand and tie the 2 nails and immerse them in the same test tube. (The other nail and test tube containing copper sulphate is only for comparison)
• Leave the apparatus for 20 minutes.
• After 20 minutes take the nails out.

Observe: The nails which were immersed are brownish in colour in comparison to the nail which was not immersed. Also the copper sulphate solution in which the nails were immersed has a lighter shade of blue.

What happened?

There was a reaction between Copper sulphate and iron in which, iron displaces copper.

     Fe(s) + CuSO₄(aq)⟶ FeSO₄(aq) + Cu(s)

Iron displaces copper because in the reactivity series it is placed higher then copper, in other words, it is more reactive then copper.

BEHOLD!!!! THE POTATO BATTERY!!!

Ever thought about making a battery would food? Don't think its possible? Let's find out!!

Materials Required:
1) 2 Galvanised nails
2) 2 Copper nails
3) 3 Jumper Wire
4) A clock with only 1 Battery required

Instructions

• Insert a galvanised nail at one end of both the potatoes.
• Now, insert the copper nail, at the other end of both the potatoes. Make sure the nails do not touch.
• Now, take the first potato and connect a jumper wire, connecting the copper nail and the POSITIVE terminal of the battery compartment of the clock.
• Connect the other jumper wire to the galvanised nail of the second potato and the NEGATIVE terminal of the battery compartment of the clock.
• Connect the third wire to the galvanised nail of the first potato and the copper nail of the second potato. 
• Now the circuit has been completed, the clock would be running.

CONCEPT: A potato battery is an electrochemical batteryl. An electrochemical battery is a battery in which chemical energy is converted to electric energy by a spontaneous electron transfer. Hence electricity is generated (with movement of electrons) and the clock starts.