What is the change in internal energy if 30 J of heat are released from a system and the system does 50 J of work on its surroundings? Use AU= Q-W. O A. 20 J O B. -20 J O C. -80 J O D. 80 J​

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:

when it gains or loses electrons

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete

according to jean piaget, in what stage of cognitive development are children able to understand conservation task?

b. preoperational

just took it