Why do lightbulbs shine, and are black holes dangerous? Try our kids’ quiz

1. Sophie, 7, asks: why do lightbulbs shine?

   1. They know it is dark and want to light up so you can see the way

   2. They are filled with magical energy that turns on when you switch them on

   3. Electricity passes through a thin wire in the bulb, which heats up and produces light

   4. They turn on when you have a good idea

2. Joel, 3, asks: why do plants need water?

   1. They need it for cell structural support

   2. They need it to make and transport their own food

   3. They need it to stay cool in hot weather

   4. They need it for all the reasons listed above

3. Teddy, 7, asks: are black holes really that dangerous?

   1. No, they’re just very dark but not dangerous

   2. Yes, if you see one and aren’t carrying a torch

   3. Yes, if you’re close to one

   4. Yes, they can be but only if you are carrying something that conducts electricity

4. Gaël, 8, asks: what is the longest movie ever and how long is it?

   1. 35 days

   2. 1 day

   3. 5 hours

   4. 3½ hours

5. 5 Ilyas, 10, asks: what is the biggest number?

   1. A billion

   2. A quadrillion

   3. A sexdecillion

   4. A googolplex

Solutions

1:C - Lightbulbs shine when an electrical current passes through a very thin wire called a filament inside the bulb. It's so thin, it’s hard for electricity to move through it – this resistance makes the wire heat up as the atoms inside it get excited, producing white-hot light., 2:D - Plants need water for a process called photosynthesis, which is how they make their own food using sunlight, water and carbon dioxide from the air. Water also helps them to keep cool in the heat and supports the cells inside the plant to keep it strong and flexible., 3:C - Black holes form when a massive star dies. If you fell into a black hole, the gravity would be so strong that you'd be torn apart. The scientist Stephen Hawking described this process as “spaghettification” because the gravity would stretch your body out like spaghetti!, 4:A - The longest movie ever made is the Swedish film Logistics. Made in 2012, it is 35 days and 17 hours long. The trailer lasts 72 minutes! , 5:D - Considered to be the biggest number in the world, a googolplex is so large that we can’t write it in normal number format.

Scores

1. 5 and above.

2. 4 and above.

3. 3 and above.

4. 2 and above.

5. 0 and above.

6. 1 and above.

Molly Oldfield hosts Everything Under the Sun, a weekly podcast answering children’s questions, out now as a book.

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