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maemo.org - Talk (https://talk.maemo.org/index.php)
-   Nokia N900 (https://talk.maemo.org/forumdisplay.php?f=44)
-   -   SAR Shield (https://talk.maemo.org/showthread.php?t=66917)

stone17 2010-12-20 23:17
Re: SAR Shield
 
Quote:
Originally Posted by zimon (Post 898116)
Actually 0.37 W per every second, don't you think?

2400 mAh / 24h * 3.7V = 0.37 VA = 0.37 W
Which would mean the battery is drained 100 mA in average constantly.
(Check: 100mA * 24 h * 60 * 60 / (60 * 60) = 2400 mAh)
:D Actually u r both wrong. The battery having 2400mAh has an energy content of 2.4Ah*3.7V=8.88Wh, which means ur device can for example have a steady power consumption of 0.37W and will than last 24h. In this context there is no such thing as W/h or W/s. W is actually J/s, i. e. a rate at which energy is used. Speaking of W/s or W/h would be the derivative, i. e. a measure at which the consumption of energy changes over time like the acceleration and velocity.

blue_led 2010-12-21 10:38
Re: SAR Shield
 
i quote myself
Quote:
2400 mAh per day = 0.1A per hour times 3,7 V = 0.37 W per hour
i lost "h" from mAh so right statement is 0.37 Wh per hour means Energy ( 1332 J ).this was the idea.
this energy is absorbed by your precious brain and unwanted corns. and giving total battery energy of 17.3 kJ please calculate SAR level [ m² / s³ ]

zimon 2010-12-21 11:06
Re: SAR Shield
 
Quote:
Originally Posted by blue_led (Post 901181)
i quote myself

i lost "h" from mAh so right statement is 0.37 Wh per hour means Energy ( 1332 J ).this was the idea.
this energy is absorbed by your precious brain and unwanted corns. and giving total battery energy of 17.3 kJ please calculate SAR level [ m² / s³ ]
Where did you get 17.3 kJ?

stone17 2010-12-21 12:55
Re: SAR Shield
 
The battery should have a total energy of 8.88Wh=8.88Jh/s=8.88J*3600s/s=32kJ...

Joseph.skb 2010-12-21 12:56
Re: SAR Shield
 
And that's equivalent to how many apples a day?

stone17 2010-12-21 13:06
Re: SAR Shield
 
Quote:
Originally Posted by Joseph.skb (Post 901249)
And that's equivalent to how many apples a day?
This is the wrong question. A beer has something about 200kJ, but the beer's energy is not absorbed by your body as it happens with the energy of the phones EM-radiation.U rather wanna know how warm the tissue around your ear will become as this or parts of this energy are absorbed while using ur phone. This could than be used as a measure of how dangerous it would be to use ur phone.

zimon 2010-12-21 13:08
Re: SAR Shield
 
Quote:
Originally Posted by stone17 (Post 901247)
The battery should have a total energy of 8.88Wh=8.88Jh/s=8.88J*3600s/s=32kJ...
Right.

Quote:
Originally Posted by zimon (Post 898116)
Actually 0.37 W per every second, don't you think?

2400 mAh / 24h * 3.7V = 0.37 VA = 0.37 W
Which would mean the battery is drained 100 mA in average constantly.
(Check: 100mA * 24 h * 60 * 60 / (60 * 60) = 2400 mAh)

The worst case scenario; all that energy would be radiated out in 500 - 3000 Mhz area (GSM,UMTS,BT,WLAN). The maximum output power is limited to 2W, so daily it would radiate 4h 26min @ 2W.

Continuing the worst case scenario, all that 32 kJ radiation daily would be absorbed by my tissues. Should I worry?

(The worse than the worst case scenario:
If all that energy (32 kJ - one day) would be converted to X-rays, I (90kg) would get about 355 Gy, which would kill me.)
Ok, "0.37 W" all the time I meant "with every second" for 24 hours.

Joseph.skb 2010-12-21 13:22
Re: SAR Shield
 
Quote:
Originally Posted by stone17 (Post 901256)
This is the wrong question. A beer has something about 200kJ, but the beer's energy is not absorbed by your body as it happens with the energy of the phones EM-radiation.U rather wanna know how warm the tissue around your ear will become as this or parts of this energy are absorbed while using ur phone. This could than be used as a measure of how dangerous it would be to use ur phone.
Thank you Stone for the note of caution. But I cannot imagine how much 8.88Wh=8.88Jh/s=8.88J*3600s/s=32kJ means. At least the reference to (a can of) beer puts things in better perspective. So, basically if we use the N900 until the battery drains dry, it would be equivalent to a can of beer? That's not too bad right? Considering we're on the phone like only a few hours max a day. I don't think using the internet or applications will have adverse effect as having the phone next to our ears and brain?

shadowjk 2010-12-21 13:43
Re: SAR Shield
 
Most of the energy is converted into heat and not EM anyway..

For example using wifi draws about 1.5W of power, but only 0.1W of that is radiated as 2.4GHz em.

Joseph.skb 2010-12-21 14:00
Re: SAR Shield
 
I'm starting to get a headache reading all these numbers than from using the N900. :rolleyes:

Would someone help to put it in simple English or Steve Jobs style?

So, basically;
We should not use our phones for x-hours/day?
Using it x-hours/day is equivalent to 1 can of beer's harm?

Sorry, I'm more of a marketing guy...so it's hard to make any meaning of these numbers.


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