[Brad Phipps]

Brad Phipps  asked the Naked Scientists:
   
Dear Naked Scientists,

I love your show! I listen every week via the mp3 podcast.

I have a question: Which is more efficient, a mechanical clock, or a digital clock?

To be more specific, let's say I have 2 small alarm clocks, both powered by a identical batteries and both kept in time by a quartz crystal. However, one has mechanical hour and minute arms that rotate, while the other has a digital LED display. Which clock's battery will last longer?

I'd be interested to hear your reasoning.
 
Thanks!
 
Brad Phipps
Columbus Ohio, USA

What do you think?

[ricbritain]

Surely it would depend on a lot of things. Like the size of the clock, arms etc. A clock will run a battery down faster if it's effectively running a large motor to turn the arms. Similarly if the battery is illuminating a large display it will use more power than a small dim display. This seems like a pretty inane question to be honest.

[graham.d]

Generally I would expect the lowest power will be for an LCD display without any back lighting. The motor driven one would probably be next and an LED display use the most power.