John is conducting an experiment that involves melting ice cubes. Which of the following is most important for John to collect reliable data? A. The outcome needs to be controlled.

B. An unbiased observer must witness the experiment.

C. Technology needs to be used to determine the results.

D. Only one variable should be tested during the experiment.

I think A not sure took this test 5  yrs ago

Explanation:

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:

answer: a) y=-8x+5

a) m= -8

b) m= -2

c) m= 7

d) m= 6