At t = 4.0 s, the elevator door opens and remains open for 5.0 s. The student immediately exerts a larger constant force on the box and the front of the box reaches the elevator door just as it starts to close. (c) Calculate the magnitude of the new force that the student exerts.

Is a copper wire a conductor or insulator?

A6.0-μf air-filled capacitor is connected across a 100-v voltage source. after the source fully charges the capacitor, the capacitor is immersed in transformer oil (of dielectric constant 4.5). how much additional charge flows from the voltage source, which remained connected during the process?

Three resistors are connected in series across a 15-v power supply. if the potential drops across resistors 1 and 2 are 4.1 volts and 3.1 volts, what is the exact potential drop (in volts) across resistor 3?