refraction

Refraction is here to be with his buddy! Anyway, let me start.

Refraction has lots to remember as compared to reflection.

This illustration basically means:

•The ray of light which travels through the incident, or first, medium and strikes the boundary, or interface, is called the incident ray.


•The ray of light which travels into the refracted, or second, medium and leaves the interface is called the reflected ray.

•A line perpendicular to the surface is imagined at the point of refraction. This line is called a normal. In this context the word normal means perpendicular. In the above diagram the normal is colored blue.

•The angle between the incident ray and the normal is called the angle of incidence, or the incident angle.

•The angle between the refracted ray and the normal is called the angle of refraction, or the refracted angle.
 

This picture means that the ray would bend towards the normal when it is travelling in a denser medium.

This picture means that the ray bends away from the normal when it is travelling in a less dense material.

reflection

Stella's back for more, this time with reflection! It's buddy, refraction, will be accompaning him later on, on the next post.

This picture says it all, right?

It basically means this

•The ray of light which strikes the surface is called the incident ray.


•The ray of light which leaves the surface is called the reflected ray.

•A line perpendicular to the surface is imagined at the point of reflection. This line is called a normal. In this context the word normal means perpendicular.

•The angle between the incident ray and the normal is called the angle of incidence, or the incident angle.

•The angle between the reflected ray and the normal is called the angle of reflection, or the reflected angle.

Notice that the angle of incidence is = to the angle of reflection.

There is this website - click here - that shows how a light beam reflects at the surface of a flat mirror. It is an animation. Simple, but it may explain it to you. Scroll down the website and you'll see the animation.
 
Have fun!

rainbows

I know I am late for this post since this topic was ages, ago, so I was thinking why not a recap! It won't hurt, would it?

Rainbows are one of the most spectacular light shows observed on earth. Indeed the traditional rainbow is sunlight spread out into its spectrum of colors and diverted to the eye of the observer by water droplets.


Most people have never noticed that the sun is always behind you when you face a rainbow. I understand it is funny but it is true.


The traditional description of the rainbow is that it is made up of seven colors - red, orange, yellow, green, blue, indigo, and violet. Actually, the rainbow is a whole continuum of colors from red to violet and even beyond the colors that the eye can see. Thank God we only have to learn the 7 colours. :D

The colors of the rainbow arise from two basic facts:

Sunlight is made up of the whole range of colors that the eye can detect. The range of sunlight colors, when combined, looks white to the eye. This property of sunlight was first demonstrated by Sir Isaac Newton in 1666.

Light of different colors is refracted by different amounts when it passes from one medium (air, for example) into another (water or glass, for example).

There are certain times when you actually see 2 rainbows. Magnificent huh?


However, not all of the energy of the ray escapes the raindrop after it is reflected once. A part of the ray is reflected again and travels along inside the drop to emerge from the drop. The rainbow we normally see is called the primary rainbow; the second rainbow is called the secondary rainbow.

Another interesting fact!

Rainbows are usually present during full moon, at night of course, called the lunar rainbow!

A full moon is bright enough to have its light refracted by raindrops just as is the case for the sun. Moonlight is much fainter, of course, so the lunar rainbow is not nearly as bright as one produced by sunlight.

More about rainbows - click here!

Heat and its Effects

Heat changes the size of a substance.

Heat - substance expands
Cool - Substance contracts

Solids

Examples: Metal ring and ball

Liquids

Examples: Glass flask containing coloured water
- Hot water
   + Liquid level rise
- Cold water
   + Liquid level drop

Gas
Examples: empty flask containg air and a drop of coloured water
- Hot hands/water
   + Coloured waster rises
- Iced water
   + Coloured water dropped

Problems

Problem

- Cause pavements to crack/ tiles pop out
Solution
- Expansion gap

Problem

It's the closest I can get

- Railway tracks wrap
Solution
- Gaps in between tracks

Problem
- Bridges expand, and may be at risk of damage
Solution

- Expansion gaps or resting on rollers

Problem
- Expansion of water pipes/ oil pipelines, causing them to burst
Solution

- Expansion bends

Problem

- Telephone wires/ cable contract in cold weather, and become taut, any may snap
Solution
- Wires are strung loosely

Uses of expansion
Riverts

- Join steel plates and girders

- Bimetallic strip
  + Thermostat
  + Thermometer

Click here for websites more about it.

real & virtual images

Frankly speaking, I am confused about what is real image and what is virtual image.
So, I have conducted a research on it, hoping that both you and I would understand it.

Real and Virtual Images



Mirrors work by changing the direction that light is moving. In a concave mirror, the light gets reflected towards the center. In a convex mirror, the light moves away. To make an image, we can trace a few rays that the light makes and see what happens to them.


Let’s start with a concave mirror. If the object is far away, the light rays come in, and then bounce and come back together. See the picture below. This is an example of a real image.

If the object is very close to the concave mirror or you use a convex mirror, the light doesn’t come back together. However, if you look at the light that comes off of the mirror and trace it back while pretending the mirror isn’t there, they will come back to a point. This is called a virtual image.

I hope it helps, but it apparantly does not help me. D:

electricity

Old Video and a little "chim".
And a little bit, okay, maybe a lot of chemistry - atoms protons, neutrons.

Reflection

It may be long winded, but it is good for you!

A word of advice, it has got some censor, that when you go to other website, it kind of stops playing.

refraction

I guess this video says it all.
I would be a better explanation then me writing it all out.

How to Help Someone Being Shocked (Tip 101)

Arhhhhhhh!
Someone is ELECTROCUTED!
What should I do?

Stay Calm or you won't be able to do anything!

No need to remember all these steps here, but please please stick a instruction Manuel at home. Preventive measure, yeah!?

Things You'll Need:

• Non-conductive material such as wood, rubber, rope or a cloth

Stopping Electrocution

1. 
   
   Step 1
   Make sure you are NOT wet or standing on a wet surface.
   
2. 
   
   Step 2
   Turn off the source of the electricity. Turning off the appliance may not stop the flow of electricity. You may need to unplug it or even turn off the circuit breaker.
   
3. 
   
   Step 3
   Use non-conductive materials to pull the victim from the electrical source.
   
4. 
   
   Step 4
   Make sure you pull the victim with the object while not touching the one being electrocuted.
   
5. 
   
   Step 5
   Place her carefully on her back and check for breathing and a pulse.
   
   

   Instructions for a Victim Who is Breathing and Has a Pulse

6. 
   
   Step 1
   Perform the following, and then seek help. Call 911 if a phone is near.
   
7. 
   
   Step 2
   Elevate the victim's feet over his head.
   
8. 
   
   Step 3
   Keep him from moving(especially his head and neck).
   
9. 
   
   Step 4
   Loosen his clothing.
   
   

   Instructions to Help a Victim Who is Not Breathing or Lacks a Pulse

10. 
    
    Step 1
    Perform 5 cycles (2 minutes each) of chest compressions on the victim. (CPR)
    
11. 
    
    Step 2
    Call 911.
    
12. 
    
    Step 3
    Recheck for a heartbeat and breathing.
    
13. 
    
    Step 4
    Resume CPR on the victim if the victim is not breathing and does not have a heartbeat. Perform rescue breathing if the victim has a pulse, but is not
    
    
    Tips & Warnings

    • If the victim is vomiting, place her on her side.
    • Do not give the victim anything to drink.
    • Do not apply anything to the burns.

having dry hands - electricity

Touching an electrical appliance with wet hands is dangerous!
Water can conduct electricity.
Also, the resistance of our skin varies from person to person and fluctuates between different times of day. In general, dry skin is a poor conductor that may have a resistance of around 100,000 Ω, while broken or wet skin may have a resistance of around 1,000 Ω.
Tah-Dahs!
Like it?

Electrocuted, scary

Watched the video? Spot the flies too! I am currently finding the person that got electrocuted, inhumane I know, but all for science. However, if you're lucky, you won't be able to watch it. :/ So after watching this video, I've got 1 question to ask. Why did the squirrel got electrocuted when the men didn't? The position of the squirrel and the guy is almost the same, so why the different outcome?



Another one! Look at the "explosion"! It is soooo bright. Thankfully, the guy didn't stand too close to it.



Haha, you are not in luck today, I found the video! You don't need to watch if you don't want. Oh, and the man is a drug addict.

Anyway, the answer is already stated in class. Whether it is human or not, it is not touching the ground or anything connecting it to the ground and thus, the circuit is broken. If we were to touch the pole or the ground, we act like a wire, allowing electricity to flow through us.