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Answer:
A dictatorship or tyranny.
Explanation:
Answer:
Hydroelectricity is a renewable energy source.
Hydroelectricity increases the stability and reliability of electricity system
Hydroelectricity helps fight climate changes.
Explanation:
If we use hydroelectricity our country would be in good climate and not a bad one. And the best facts it is renewable.
Answer:

Explanation:
given data:
refractive index of lens 1.50
focal length in air is 30 cm
focal length in water is -188 cm
Focal length of lens is given as
![\frac{1}{f} =\frac{n_2 -n_1}{n_1} * \left [\frac{1}{r1} -\frac{1}{r2} \right ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%7D%20%3D%5Cfrac%7Bn_2%20-n_1%7D%7Bn_1%7D%20%2A%20%5Cleft%20%5B%5Cfrac%7B1%7D%7Br1%7D%20-%5Cfrac%7B1%7D%7Br2%7D%20%20%20%5Cright%20%5D)
![\frac{1}{f} =\frac{n_{g} -n_{air}}{n_{air}} * \left [\frac{1}{r1} -\frac{1}{r2} \right ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%7D%20%3D%5Cfrac%7Bn_%7Bg%7D%20-n_%7Bair%7D%7D%7Bn_%7Bair%7D%7D%20%2A%20%5Cleft%20%5B%5Cfrac%7B1%7D%7Br1%7D%20-%5Cfrac%7B1%7D%7Br2%7D%20%20%20%5Cright%20%5D)
![\frac{1}{f} =\frac{n_{g} -1}{1} * \left [\frac{1}{r1} -\frac{1}{r2} \right ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%7D%20%3D%5Cfrac%7Bn_%7Bg%7D%20-1%7D%7B1%7D%20%2A%20%5Cleft%20%5B%5Cfrac%7B1%7D%7Br1%7D%20-%5Cfrac%7B1%7D%7Br2%7D%20%20%20%5Cright%20%5D)
focal length of lens in liquid is
![\frac{1}{f} =\frac{n_{g} -n_{l}}{n_{l}} * \left [\frac{1}{r1} -\frac{1}{r2} \right ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bf%7D%20%3D%5Cfrac%7Bn_%7Bg%7D%20-n_%7Bl%7D%7D%7Bn_%7Bl%7D%7D%20%2A%20%5Cleft%20%5B%5Cfrac%7B1%7D%7Br1%7D%20-%5Cfrac%7B1%7D%7Br2%7D%20%20%20%5Cright%20%5D)

rearrange fro


