A 16-Ω resistor is connected in series with another resistor across a 12-V battery. The current in the circuit is 0.42 A. Calculate the value of the unknown resistance.

unknown resistance=12.6ohms

Explanation:

Known resistance(r)=16ohms

Unknown resistance(r)=a

Voltage(v)=12V

Current(I)=0.42A

Total resistance in series connection is r=16+a

From ohms law v=I x r

12=0.42 x (16 + a)

Divide both sides by 0.42

12 ➗ 0.42=(0.42x(16+a)) ➗ 0.42

28.6=16+a

a=28.6-16

a=12.6ohms

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:

see earlier answer