Which statement best describes heating by conduction?

A.) Air molecules touch the warm ground, heating them up

B.) Air at the equator rises and sinks at the poles

C.) Sunlight travels through space without the aid of fluids or solids

D.) Warm air rises and takes heat with it; eventually it cools and sinks

Hi K12

A

Air molecules touch the warm ground, heating them up is the best statement best describes heating by conduction

Explanation:

Conduction occurs when a molecule that is close together pass along energy due to the bombardment between them as they gain kinetic energy. In this case, particles of the warm ground have higher kinetic energy than those of the air. When the molecules of the two collide the higher kinetic energy of the ground molecules is transferred to the air molecules . This is how the air also gets warmer.

Choices B & D show heat transfer by convection while choice C shows heat transfer by radiation.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

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: