Answer:
The lenses with different focal length are four.
Explanation:
Given that,
Radius of curvature R₁= 4
Radius of curvature R₂ = 8
We know ,
Refractive index of glass = 1.6
When, R₁= 4, R₂ = 8
We need to calculate the focal length of the lens
Using formula of focal length

Put the value into the formula



When , R₁= -4, R₂ = 8
Put the value into the formula



When , R₁= 4, R₂ = -8
Put the value into the formula



When , R₁= -4, R₂ = -8
Put the value into the formula



Hence, The lenses with different focal length are four.
- Speed is the rate of change of distance with time while velocity is the rate of change of displacement with time.
- Speed is a scalar quantity while velocity is a vector quantity.
- Speed cannot be negative but velocity can be negative.
Hope you could get an idea from here.
Doubt clarification - use comment section.
Answer:
C. over land in polar regions.
The Sun's gravitational pull keeps our planet orbiting the Sun <span>in a nice nearly-circular orbit.</span>