Athin spherical glass shell in air is filled with an unknown liquid. a parallel light beam is incident on the shell, and it is observed that the light is brought to focus on the surface of the shell directly opposite. what is the refractive index of the liquid?

the anwser is "n=2" but i'm not sure how this was calculated. i was thinking of using snell's law and small angle approximation considering that this is a thin lens we're working with, but then again my brain doesn't physics very well so i have no idea if this should even be considered for this kind of question. !

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:

b.a device that inputs heat into a cool object