<em>500 sec</em>
<em>8 min 20 sec</em>
<em>Hi there !</em>
<em />
<em>8 m ................ 1 s </em>
<em>4000 m ........ x s</em>
<em>x = 4000m×1s/8m = 500 sec = 8 min 20 sec</em>
<em />
<em>Good luck ! </em>
Answer:
17.4 cm
Explanation:
Power of lens = +1.75 diopters
Focal length of lens
![f=\frac{100}{1.75}=\frac{400}{7}](https://tex.z-dn.net/?f=f%3D%5Cfrac%7B100%7D%7B1.75%7D%3D%5Cfrac%7B400%7D%7B7%7D)
This is a convex lens as focal the diopter given is positive which makes the focal length positive. Image distance will be negative.
v = -25
![\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\\\Rightarrow \frac{1}{-25}-\frac{1}{u}=\frac{1}{\frac{400}{7}}\\\Rightarrow -\frac{1}{u}=\frac{7}{400}+\frac{1}{25}\\\Rightarrow \frac{1}{u}=-\frac{7}{400}-\frac{1}{25}\\\Rightarrow \frac{1}{u}=-0.0575\\\Rightarrow u=-17.4\ cm](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bv%7D-%5Cfrac%7B1%7D%7Bu%7D%3D%5Cfrac%7B1%7D%7Bf%7D%5C%5C%5CRightarrow%20%5Cfrac%7B1%7D%7B-25%7D-%5Cfrac%7B1%7D%7Bu%7D%3D%5Cfrac%7B1%7D%7B%5Cfrac%7B400%7D%7B7%7D%7D%5C%5C%5CRightarrow%20-%5Cfrac%7B1%7D%7Bu%7D%3D%5Cfrac%7B7%7D%7B400%7D%2B%5Cfrac%7B1%7D%7B25%7D%5C%5C%5CRightarrow%20%5Cfrac%7B1%7D%7Bu%7D%3D-%5Cfrac%7B7%7D%7B400%7D-%5Cfrac%7B1%7D%7B25%7D%5C%5C%5CRightarrow%20%5Cfrac%7B1%7D%7Bu%7D%3D-0.0575%5C%5C%5CRightarrow%20u%3D-17.4%5C%20cm)
∴ The new near point is 17.4 cm
The kinetic energy K given to the helium nucleus is equal to its potential energy, which is
![E=q \Delta V](https://tex.z-dn.net/?f=E%3Dq%20%5CDelta%20V)
where q=2e is the charge of the helium nucleus, and
![\Delta V](https://tex.z-dn.net/?f=%5CDelta%20V)
is the potential difference applied to it.
Since we know the kinetic energy, we have
![E=K=85~keV=q \Delta V](https://tex.z-dn.net/?f=E%3DK%3D85~keV%3Dq%20%5CDelta%20V)
and from this we can find the potential difference:
It is the branch of science, in which we study different phenomena of atmosphere including climate and weather.