How does the Doppler effect explain why a siren's pitch increases as it approaches you? A. The siren moves away from sound waves it has already produced, increasing their wavelength. B. The siren moves closer to sound waves it has already produced) decreasing their wavelength C. The siren moves away from sound waves it has already produced decreasing their wavelength, D. The siren moves closer to sound waves it has already produced, increasing their wavelength

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?