The distance of an illuminated object from its light source is doubled while the luminous flux remains constant. Which is true of the illuminance on the object?
A)The illuminance will be halved.
B)The illuminance will quadruple.
C)The illuminance will be multiplied by the square root of 2.
D)The illuminance will be quartered the

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:

a, c, d, e are all applying about success strategies.

the right answer is 0.3 meters per second