Science Made Simple 2- Ammu & Kanha’s Crown

The long-awaited vacations had begun. But Seema knew she wouldn’t have rest or find free time- mending her three naughty kids by itself would take a lot of time.

“Mom…Mom…”, Seema could feel the impatience in Ammu’s voice. “Mom, see our Kanha wearing the peacock feather….come, come. See what we have done.”

“From where did you get the feather??”, Seema enquired.

“You first come and see”, Ammu grabbed her hand.

“Wow”, Seema could see a colourplay on the crown of Kanha in the drawing-room. How the children placed it perfectly well on the picture of the Lord, she thought, feeling proud of the children. Five to six children were playing in the courtyard with a basin of water and a piece of mirror.

“Rainbow rainbow high and bright, rainbow rainbow made of light”, sang Chinnan (the youngest of them all)- as she clapped in amusement.

“Aunty, we made rainbow without rain”, grinned Golu- Appu’s friend.

“Violet, indigo, blue, green, yellow, orange, red”, Chinnan continued singing in excitement.

“Okay…tell me how you made it?” Seema enquired.

“Appu placed a mirror in water and there appeared a rainbow”, replied Ammu.

“Oh, so simple?”, asked Seema.

“Yessss”, came the reply in chorus.

“My teacher asked us to try this, Mom. She told us here refraction and reflection of light happens and she said sunlight is made of seven colours” exclaimed Ammu.

“Yes, that is right”, Seema replied.

“I know reflection. In a mirror…reflection happens. But what is ree-frack- shun??”, asked Ammu.

“Bending of light when medium of transmission changes is refraction”, Appu defined it absolutely well.

“I will show you what refraction is, give me your pencil”, Seema said putting the pencil in the water in the glass tumbler. “Now look at the pencil”, Seema looked at Ammu.

“Oh, it has bended”, exclaimed Ammu.

“It looks bent. We can see an object if there is light. Here, half of the pencil is in air and half in water. Light has entered from air to water. In water, the speed of light is less, so it bends…and that is refraction.”

“Aunty, if sunlight has seven colours, we have sunlight all around us…why can’t we see the colours??” questioned Golu.

“Yes…why can’t we see the colours always”, everyone asked.

Now Seema knew, there was no other escape than explaining in greater detail. “That’s because light travels at tremendous speed… at 3 lakh km/s.”

“Oh, such a great speed…Our car can move 240km/ hr maximum. It means only 66 m/s”, Appu calculated quickly.

“The fastest rocket can travel only 3.6 lakh km/hr”, Golu (very good in G.K.) remarked.

“Yes, light is the fastest moving thing in this universe. It can travel around the Earth 7.5 times in one second”, shared Seema.

“Yes, so our eyes can’t catch those colours separately so quickly”, said Appu.

“When light passes from air to water, its speed decreases. It bends, and since different colours have different wavelengths, they bend in different angles. So white light splits in water…as you do in your lab in a glass prism. The colour receptor in our brain catches these and we see the colours” added Seema.

“But why is it that violet bends the most, and we see it on the lowest side?” Ammu was getting more interested.

“Good observation Ammu. Amongst the colours, violet has the highest wavelength and red….the lowest. So we see red at the top, and violet at the bottom of the rainbow”, explained Seema.

“So why is there a mirror kept to reflect the diffracted light? In the sky, there is no mirror”. Ammu was never content unless she understood everything clearly.

“In the sky, light is reflected by water droplets itself dear…that’s called total internal reflection. A diamond sparkles due to total internal reflection” answered Seema.
“If you’ve ever noticed, dewdrops also sparkle in the morning at the tip of grassblades” added Seema.

“Mom, if we catch these colours and converge them, shall we get white light??”, asked Ammu.

“Yes, of course”, we can make a colour wheel and see that later, okay?”, said Seema.

“Okay” smiled Ammu.

The children were happy. Too many questions and ideas would still be playing in their minds, Seema was sure.

“One day I will travel in the wings of light and cover the Earth and Heaven”, Ammu’s imagination had no limits.
“I will also come with you, and we will take Amma too”, both the girls had stepped into their fairy world!

GREG RAKOZYMy children from JNV Kasaragod, Ratheesh. T. P. and Simmy Ratheesh who did this experiment for their son, photographed it and allowed me to use the picture for this series.

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