¿ìè¶ÌÊÓƵ

In a bin full of old batteries awaiting recycling, what is the probability that a closed circuit will form, allowing electrical current to flow and potentially cause a fire?

Mark Readman, Manchester, UK

We pay £25 for every answer published in ¿ìè¶ÌÊÓƵ. To answer this question – or ask a new one – email lastword@newscientist.com.

Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.

¿ìè¶ÌÊÓƵ retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.

You can also submit answers by post to: The Last Word, ¿ìè¶ÌÊÓƵ, 25 Bedford Street, London WC2E 9ES.

Terms and conditions apply.