xvxvxv

where are you ! 

I'm waiting !!! 

David 

in your first answer you write 

 Note: the actual resistance is slightly lower than the calculation. The electrical resistance nature of tungsten based filaments is non-liner, and produces a slightly lower resistance at lower temperatures. The lower resistance results in a higher current for the same voltage. This is probably why the answer indicates 0.98 instead of 0.97

what is the   "electrical resistance nature"   ...  if there is additional resistance than we calc the current will be lower ! 

In question 3 we multiply the two brackets  because the word " and " in the question ؟ 

is there any law for refraction ! ? 

yes ... nice my friend .. 

I will read more about refraction 

and you mean 194 watt not 192 ... right ? 

thanx 

what about the refractive  !! why the red is the least 

I can't understand it ! 

Now the bulb operated at 200 v and it power is 280 

so I can find the current by   I=P/V  ..... I=280/200 ... I = 1.4 A 

I want to understand my mistake in this way ! 

also in question 25 ! why the red ..؟ 

I'm based on this law  dsinx=mL      x :- is the angle   and  L :- is the wave length ! ? 

In question number 1  why I can't use   P=V.I !!