The temperature of an incandescent lightbulb is 2500 k. assuming the filament to be blackbody, determine the fraction of the radiant energy emitted by the filament that falls in the visible range

To solve this problem it is necessary the concepts related to radiant energy emitted by the bodies and their method to find it through the Blackbody radiation functions table.

From the given values we have that the temperature is 2500K and that the visible range of the electromagnetic spectrum extends from

With the wavelength and temperature we can find the relationship

then

From blackbody radiation functions table (attached) we have that

In the case of the second wave

From the table,

We can calculate the fraction of radian energy emitted by,

Therefore about 5% of the radiation emitted by the filament of the lightbulb falls in the visible range.

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards