Three resistors of 3.3 kΩ, 4.7 kΩ and 3.9 kΩ are connected in series across a 12 V battery
a. What is the equivalent resistance?
b. What is the current through the resistors?
c. Find the total potential difference across the three resistors.

Explanation:

A.) equivalent resistance

Equivalent resistance ( Rt ) in a series connection is sum of all resistance.

Rt = 3300 + 4700 + 3900

= 11900 ohms

= 11.9 k ohm

B.) current is constant across the whole circuit if it is in series .

current = potential difference ÷ total resistance

current = 12 / 11900 = 0.00100 Amphere

= 0.1 mA

C. potential difference ( v ) across the circuit =

current( i ) × resistance ( Rt )

=》v = 0.1 × 0.001 × 11900 = 12 volts

the one with the highest speed

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: