David is 5 years younger than his brother Jacob. Jacob is twice as old as their sister Claire.
1. Select all expressions that represent the sum of their ages.
d - 5 + + 20
¢ + 2e + -5)
2e + I + (-5)
U-5) +/+
4 + ( + 5) + (+5)

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 and b sometimes have a positive value

the closer the planet is to the sun, the larger the gravity

i believe the answer is a hope it and is correct