What is the focal length of the eye-lens system when viewing an object at infinity? Assume that the lens-retina distance is 2.0 cm . Follow the sign conventions. Express your answer using two significant figures and include the appropriate units.

Focal length of the eye-lens is 2.0 cm

Explanation:

Given:

An eye-lens system which will follow converging lens (convex lens) sign conventions and knowing that lens-retina distance is the image distance.

Object distance, =

Image distance, = cm

We have to find the focal length.

Lets say that the focal length is .

Lens Formula:

⇒

Sign-convention:

We will follow the Cartesian coordinate,placing the lens at the origin of the plane, optical center is at now as the object will be towards negative x-axis so it is negative others are on the right side of the origin so they are positive.

Using the lens formula:

⇒

⇒      

⇒         ...as and there is no so it is zero only.

⇒ cm

So the focal length is 2.0 cm with two significant figures.

i believe the answer is a

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation: