Hanukkah Menorah
Light the Hanukkah candles in a window, one more each night.
How to play
- Tap the raised shamash in the middle of the menorah to light it.
- Drag the lit shamash to a candle and hold its flame at the wick, or simply tap the candle. By custom the newest candle, on the left, is lit first.
- Tap the box of candles on the sill to set out the next night. Candles are added from right to left, one more each night.
- Tap the little clock to make time run 10 or 60 times faster and watch the candles burn down. Lab has the fuel, the flame power and a draught from the window.
Challenges
- Light the shamash, then use it to light the first candle
- On the third night or later, light every candle in order, newest (leftmost) first
- Keep all of tonight’s candles burning for half an hour, the customary minimum
Try this
- Raise the flame power from 40 W to 80 W and watch the burn time halve: a hotter flame burns its wax twice as fast.
- Switch to olive oil lamps. Olive oil releases a little less energy per gram than paraffin wax, so the same flame uses up more fuel.
- Turn up the draught from the window and watch the flames lean and flicker. Moving the shamash makes its flame trail behind it.
Fun facts
- Hanukkah lasts eight nights. It begins on the 25th of the Hebrew month of Kislev, which usually falls in late November or December.
- A hanukkiah has nine branches: eight for the nights of Hanukkah and one for the shamash, the helper candle used to light the others.
- Many families place the menorah in a window or by the door, so its light can be seen from outside.
- The candela, the unit of luminous intensity, is roughly how bright an ordinary candle is.
How a candle flame burns, and how long it lasts
Hanukkah, the Jewish festival of lights, remembers the rededication of the Temple in Jerusalem in the 2nd century BCE. Tradition tells that the oil found there was enough for only one day, yet it burned for eight. Each evening of Hanukkah families light one more candle in the hanukkiah, recite blessings, and often enjoy foods fried in oil such as latkes and sufganiyot. Customs vary between communities: some light oil lamps, some light one menorah per person, and families have their own melodies and traditions. This scene keeps things calm and simple: a window, a snowy street and the growing row of lights.
What is actually burning?
A candle does not burn its wax directly. The flame’s heat melts a small pool of wax around the wick, and the liquid wax climbs the wick by capillary action, the same effect that draws water up a paper towel. Near the top of the wick the wax turns into vapour, and it is this vapour that burns as it mixes with oxygen from the air.
The flame has layers. At its base, where fuel and air mix well, burning is clean and faintly blue. Higher up, tiny specks of unburnt carbon soot are heated to well over 1,000 °C and glow yellow, which is where most of a candle’s light comes from. Hot gas rises and draws fresh air in from below, stretching the flame into its familiar teardrop. That is also why the flames lean in a draught and trail behind the shamash when you move it.
How long will it last?
Every gram of fuel releases a fixed amount of energy when it burns: about 46 kilojoules for paraffin wax and about 39 for olive oil. A small candle flame gives out heat at roughly 40 to 80 watts. Divide the power by the energy per gram and you get the burn rate, ṁ = P / ΔH. At 65 W a paraffin candle burns about 5 grams of wax an hour, so a slim candle weighing about 4 grams lasts around 48 minutes. Double the flame power and the candle lasts half as long.
For the curious
The simulated candles are 8 mm across and 9 cm long, holding about 4.1 g of wax (density 0.9 g/cm³). Each frame the remaining fuel falls by ṁ·Δt, and the candle shortens to match. A wick catches when another flame is held against it for about a quarter of a second, long enough to vaporise a little wax. Each flame also lights the windowsill and the menorah through a many-light shader, in which brightness falls with the square of the distance.
Questions people ask
Why does a Hanukkah menorah have nine candles?
Eight candles stand for the eight nights of Hanukkah, recalling the story of oil that lasted eight days. The ninth, the shamash or helper, is used to light the others and is usually set apart, higher or in the middle.
In what order are Hanukkah candles lit?
A common custom is to place the candles from right to left, adding one each night, and to light them from left to right, so the newest candle is lit first. The shamash is lit first and used to light the rest. Customs vary between communities.
How long should Hanukkah candles burn?
By custom the lights should burn for at least half an hour after nightfall. Small Hanukkah candles are made to last a little longer than that.
