Aconcave mirror with a focal length of 30 cm is used to form an image that is 30 cn behindo the mirror. what is the object distance? vy a) +20 cm b)+15 cm c)+60 cm d)+30 cm e)+58 cm

The object distance is

Explanation:

According to the Descartes equation, you have:

[object distance]

[negative image distance from being behind]

[focal length]

Clearing in the Descartes equation:

The object distance is cm

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: