Five questions about Apple Watch

Tim Cook unveils the Apple Watch in September 2014 Image copyright Getty Images

Apple events are always preceded by a huge amount of feverish speculation as what cynics call the reality distortion field is deployed.

But today's show at the Yerba Buena Arts Centre in San Francisco might well break the internet, such is the excitement and anticipation. And this for the second event about a device first unveiled last September. So what do we need to know this time? Here are five questions I will be hoping to see answered...

How much?

We know that the starting price of the basic sports model will be $349 (£230). What we don't know is what that means in other currencies, and how much the rest of the range will cost. It's thought the gold-cased version could cost as much as $10,000 (£6,614), and it looks as though even the basic models will be priced at a level which will make it a far-from-casual purchase. By contrast, the new Pebble Time, the latest version of the most popular smartwatch to date, is going to cost $199 (£132).

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Media captionThe BBC's Jeremy Howell asks whether the Apple Watch will jump-start the smartwatch sector

How long will the battery last?

Apple has been signalling that the watch will need recharging every night - and there are some hints that really heavy users could find they run out of juice midway through the day. We've got used to that with smartphones - will we be so happy about yet another gadget which needs constant recharging? Some smartwatches last much longer on a charge, notably the Withings Activite Pop which has a battery lasting eight months. But they can do much less, which brings us to our key question….

What can it actually do?

The demos we've seen so far show the Watch providing some of the notifications you get on an iPhone, combined with tracking your physical activity and your heart rate. That's similar to what plenty of other devices do, but what will be key is the user interface. Apple has shown in the past - notably with the iPhone and iPad - that it can take existing technologies and make them far more attractive and easy to use.

Can I pay with it?

We know that the mobile payments service Apple Pay will work with the watch, and could provide a compelling use for it. Right now, that is only available in the US, but it's thought it could be coming to the UK this year. So far, Apple Pay has been a big hit, but has also been popular with fraudsters, although that appears to be the result of lax identity checks by the banks rather than a fault with the technology. Today's event provides an ideal opportunity for Apple to take its mobile payments system to the next stage, while providing reassurance about security.

How many does Apple hope to sell?

This is one question unlikely to be answered today. But here's a safe bet - within a week of the Apple Watch going on sale it will be the best selling device on the market. But that is not a high hurdle to clear when fewer than five million smartwatches were sold in 2014, according to research firm Canalys. Analysts predictions for how many devices Apple will sell this year range from eight million to more than 40 million. The bigger question will be how many are sold in 2015 - only then will we know whether the Watch is the Next Big Thing or just another smartphone accessory.