Series Circuit and Parallel Circuit

In the picture

1. 1The battery on the left board pushes current around one single loop.
2. 2The first bulb on that loop glows dimly because it shares the one current path with the other bulb.
3. 3The wire between the two bulb holders carries the very same current through both of them.
4. 4The solder bead on the right board splits the current into two separate branches.
5. 5The bulb on its own branch gets the full battery voltage, so it glows brightly.

Examples

• Old Christmas string lights wired in series: one burnt-out bulb leaves the whole strand dark.
• The lamps in a room are wired in parallel: switching one off leaves the others shining.

Quiz: Series Circuit and Parallel Circuit (Age 13)

1. 1

   Two bulbs are joined to a battery in one single loop of wire. What is true about the current?

   • Each bulb has its own separate current.
   • The very same current passes through both bulbs.
   • The current is used up by the first bulb, so none reaches the second.
2. 2

   Why does a bulb on its own branch glow more brightly than a bulb that shares one loop with a second bulb?

   • It sits closer to the battery.
   • Its branch is made of thicker wire.
   • It receives the full battery voltage instead of sharing it.
3. 3

   Two bulbs are lit on one single loop. Someone unscrews one of them. What happens to the other bulb?

   • It goes out, because the only path has been broken.
   • It stays lit, because it still has a path of its own.
   • It stays lit but becomes dimmer than before.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.