Answer:
The focal length fe of the eyepiece is <em>2.86 cm</em>
Explanation:
Since we are given the telescope's magnification and the length of the tube, we can use the expressions
<em>M = f_o/fe (1)</em> and
<em>l = f_o + fe (2)</em>
where
- M is the telescope's magnification
- l is the length of the tube
- fe is the focal length of the eye-piece
Rearranging equation (2) to make f_o the subject of the formula, we get
<em>f_o = l - fe</em>
Substituting the above equation into equation (1) we get
<em>M = (l - fe)/fe ⇒ fe = l/(M +1)</em>
<em> ⇒ fe = 60/(20 + 1)</em>
⇒ <em>fe = 2.86 cm</em>
Answer:
hi sandra!!
Explanation:
the number 3 is the correct!!
The Aurora is an incredible light show caused by collisions between electrically charged particles released from the sun that enter the earth’s atmosphere and collide with gases such as oxygen and nitrogen. The lights are seen around the magnetic poles of the northern and southern hemispheres.
Auroras that occur in the northern hemisphere are called ‘Aurora Borealis’ or ‘northern lights’ and auroras that occur in the southern hemisphere are called ‘Aurora Australis’ or ‘southern lights’.
Auroral displays can appear in many differents colours, but green is the most common. Colours such as red, yellow, green, blue and violet are also seen occasionally. The auroras can appear in many forms, from small patches of light that appear out of nowhere to streamers, arcs, rippling curtains or shooting rays that light up the sky with an incredible glow.
A = <0,1>
B = <-1,3>
then
A + B = < 0+-1 , 1+3 > = <-1, 4>
magnitude = sqrt( (-1)^2 + (4)^2 )
= sqrt( 1 + 16)
= sqrt(17)
