Firework Science

1. Firework Art in a Cup of Milk  (or indeed a plate of milk)

This is how L and I used our special time together this morning.  He is fascinated by magic tricks at the moment and I thought it would be fun to investigate some of the sciencey “magic” out there, since it would appeal to him on all levels.  This was the first one I came across that I didn’t think I’d need to practise on my own beforehand, and I also thought it would tie in nicely with bonfire night coming up.

To make our firework art, we poured milk on a plate and added drops of food colouring around the edges.

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We used the three primary colours as I wanted to reinforce our colour mixing activities for L, although we didn’t actually talk about it, I just let him observe what happened.

First, we touched a clean toothpick to the centre of the dish, to prove nothing happened.  We then used the “magic potion” (we both knew the secret we were not going to tell Daddy and N – the potion was washing up liquid).   The magic began immediately as the colours started to move and mix…

And our magic fireworks appeared in the milk!

This was actually really cool – the soap separates the fat from the water in the milk (to get technical, one end of the soap molecule attaches to the water molecules whilst repelling the fat), causing the whole thing to ripple and the colours to merge.  It really did look like exploding fireworks.  There was no need to touch it once the process had started, but having watched the effect, L had fun “drawing” with the soap-coated toothpick and experimenting to get different effects.

We did this twice, and found that gel colouring worked better than liquid food colouring.  And L’s art work left a beautiful residue on the plate.  A lovely idea would be to take an imprint of this with blotting paper to make a firework picture that can be kept.

2.Fireworks in a Jar

Our next experiment wassimilar to the BFG Dream Jars we made for Roald Dahl Day in September – with a slight difference in that this time we called them fireworks in a jar, and that we kept it simpler (didn’t add salt, and only made one jar to observe in detail) focused more on the scientific explanation.

Two Eager Scientists (and a jar of water)

This time we just made one jar of fireworks.  We filled a large jar with water, about 3/4 full.  We then added some drops of food colouring in several different colours to some cooking oil.  We took turns to mix it up (the taking turns part was very important to our scientists):

 

We added the oil and colouring mixture to the water, and watched…

We saw that the oil and colouring sat on top of the water

Followed by a “firework display” in the jar, as globules of colour began to sink out of the oil and through the water.

Both L and N could predict what would happen (I was pleased that the dream jars had stuck in their minds, even N’s three year old mind) but were still delighted with the fireworks!

3. Defying Gravity

This has precisely nothing to do with Bonfire Night, but is linked to our science magic.  L and I defied gravity by turning a glass of water upside down without spilling it:

There is huge debate on the internet as to how this trick works – google if you’re interested! – but my understanding is that the atmospheric pressure is equal to the downward pressure of the water on the piece of card.

We discovered that breaking the seal (letting air in) caused the card and the water to fall, but we didn’t experiment any further.  When he is a bit bigger and less scared we might play with different sizes of glass, different strengths of card, different levels of water.  For now, I’m still impressed, and I still think this is magic!

 

 

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