Making bulbs brighter

1. READ/play the text
2. CLICK the picture (and video)
3. TRY this:

Q1: How do you make a bulb shine most brightly?

[Answer]

If you were to make the circuit shown here and switch it on, the bulbs would light more dimly than if the circuit had just one bulb.

This is because the bulbs and the batteries are not matched. There are two 3V bulbs, so they need 6V of electricity, but there are only two 1.5V batteries in the circuit (=3V). You needed four batteries to make 6V and match the bulbs.