Apoint charge of 4 μс is located at x =-30 cm, and a second point charge of-10 pc is located at x-+4.0 cm. where should a third charge of +6.0 pc be placed so that the electric field at x = 0 is zero?

it is to be placed at x = 3.1 cm

Explanation:

Electric field due to charge placed at x = -30 cm

so we have

towards left

now electric field due to another charge placed at x = 4 cm

towards Right

now we need electric field due to 6 pC must be equal to

towards Left

so we have

so it is to be placed at x = 3.1 cm

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: