First question (upper left): 1/Req = 1/12 + 1/24 = 1/8 Req = 8 ohms Voltage is equal through different resistors, and V1 = V2 = 24 V. Current varies through parallel resistors: I1 = V1/R1 = 24/12 = 2 A. I2 = 24/24 = 1 A.
Second question (middle left): V1 = V2 = 6 V (parallel circuits) I1 = 2 A, I2 = 1 A, IT = 2+1 = 3 A. R1 = V1/I1 = 6/2 = 3 ohms, R2 = 6/1 = 6 ohms, 1/Req = 1/2 + 1/1, Req = 2/3 ohms
Third question (bottom left): V1 = V2 = 12 V IT = 3 A, meaning Req = V/It = 12 V/3 A = 4 ohms 1/Req = 1/R1 + 1/R2, 1/4 = 1/12 + 1/R2, R2 = 6 ohms I1 = V/R1 = 1 A, I2 = V/R2 = 2 A
Fourth question (top right): 1/Req = 1/20 + 1/20, Req = 10 ohms IT = 4 A, so VT = IT(Req) = 4*10 = 40 V Parallel circuits, so V1 = V2 = VT = 40 V Since the resistors are identical, the current is split evenly between both: I1 = I2 = IT/2 = 2 A.
Fifth question (middle right): 1/Req = 1/5 + 1/20 + 1/4, Req = 2 ohms IT = VT/Req = 40 V/2 ohms = 20 A V1 = V2 = V3 = 40 V The current of 20 A will be divided proportionally according to the resistances of 5, 20, and 4, the factors will be 5/(5+20+4), 20/(5+20+4), and 4/(5+20+4), which are 5/29, 20/29, and 4/29. I1 = 20(5/29) = 100/29 A I2 = 20(20/29) = 400/29 A I3 = 20(4/29) = 80/29 A
Sixth question (bottom right): V2 = 30V is given, but since these are parallel circuits, V1 = VT = 30 V. Then I1 = V1/R1 = 30 V/10 ohms = 3 A. I2 = 30 V/15 ohms = 2 A. IT = 3 + 2 = 5 A 1/Req = 1/10 + 1/15, Req = 6 ohms
1. Hot air is less dense and has moved upward allowing cool air to move downward which is less dens
(Convection current)
2. The ceiling has transferred heat to him by radiation.
Explanation:
During the day when air is heated as a result of the ceiling transferring heat to it, it becomes less dens and it gains energy, which make it lighter in weight than cooler air, this hot air moves upward allowing cooler air to move downward.
This is because the speed of a wave is determined by the medium through which it is passing. When light speeds up as it passes from one material to another, the angle of refraction is bigger than the angle of incidence. For example, this happens when light passes from water to air or from glass to water ❤