"Heat conduction to skin": Suppose 175 W of heat flows by conduction from the blood capillaries beneath the skin to the body's surface area of 1.5 m2. If the temperature difference is 0.70°C, estimate the average distance of capillaries below the skin surface.

Explanation:

Thermal conductivity of human skin K = 21 W / m²

Formula for heat conduction

Q = KA ( θ₂ - θ₁) / d

A is surface area ,  θ₂ - θ₁ is temperature difference , d is thickness .

Putting the values

175 = 21 x 1.5 x .70 / d

d = .126 m

= 12.6 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:

the answer is a. hope this .