An AC voltage source, with a peak output of 72 V, results in dissipation of energy in a resistor at rate of 140 W. What is the value of the resistance?

18.51 Ω

Explanation:

Power dissipated in electric circuits is given by P = IV

But, V = IR And I = V/R

P = (V/R) V = V²/R

But this is an AC circuit, and the voltage in the power dissipated equation is the DC voltage.

DC voltage of the AC circuit = Vrms = (Vpeak)/√2 = 72/√2 = 50.912 V

P = V²/R

R = V²/P = 50.912²/140 = 18.51 Ω

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:

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.