If one doubles the emfs in a circuit and doubles the resistances in the circuit at the same time, what happens to the currents through the resistors? assume there are only emfs and resistors in the circuit.

Same

Explanation:

Let R be the resistance of the cell and E be the emf.

Let i be the current in the circuit.

i = E / R       (1)

Now emf and resistance be doubled.

so, i' = 2E/2R = E/R

So, i' = i    (From equation (1)

Current remains same.

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: