+30p While a police car moves at a speed of 30m / s, the driver hears at a single-note frequency of 650Hz. One of the police cars passes in front of someone waiting in the traffic light and gets closer to the other. Calculate the wavelengths and frequencies of a) approaching, b) driving away sirens.

If you mix chlorine lithium in nickel together which two elements would be the most reactive

In a voltaic cell, electrons flow from the (positive/negative) to the (positive/negative) terminal.

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e