a glass lens has a convex surface with a radius 25.0 cm and a concave surface with radius 50.0 cm with the glass refraction = 1.51 calculate the focal length
30cm
To calculate the focal length of a lens with a convex and concave surface, you can use the lens maker's formula:
1/f = (n - 1) * (1/R1 - 1/R2),
where:
- f is the focal length of the lens,
- n is the refractive index of the glass,
- R1 is the radius of the convex surface,
- R2 is the radius of the concave surface.
In this case, n = 1.51, R1 = 25.0 cm, and R2 = 50.0 cm.
Substituting the values into the formula:
1/f = (1.51 - 1) * (1/25 - 1/50).
Simplifying the equation:
1/f = 0.51 * (2/50 - 1/50),
1/f = 0.51 * 1/50,
1/f = 0.0102,
f = 1 / 0.0102.
Therefore, the focal length of the lens is approximately 98.04 cm.