A 12 V battery applies a potential difference to three resistors in series. If the potential at point P is 0.0 V, the potential at point B is:

This question is incomplete, the complete question is on the image uploaded along this answer.

the potential at point B is 5 V, Option d) is the correct answer

Explanation:

Given that;

from the image;

R = 3 + 4 + 5 = 12 Ω

so I = 12/12 = 1 A

Q = 0 + 12 = 12 V

now

VA - VQ = - I × 3 = -3 V

VA = VQ - 3 =  12 - 3 = 9 V

VB - VA = - I × 4Ω = - 4 V

⇒VB = VA - 4 = 9 V - 4 V = 5 V

Therefore the potential at point B is 5 V

Option d) is the correct answer

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: 31, 5556. 952 seconds