25. Coordination. A pair of identical speakers emit spherical coherent waves with a wave-
length of 4 units. These are placed at different positions along the xy-plane. In which
speaker placement will you have constructive interference at the origin?
A. (0, 1) and (5, 0)
B. (2, 0) and (-3, 0)
C. (1, 0) and (1, -1)
D. (-4, 0) and (1, 0)
26. Alin ang naiba? Which of the following situations will not lead to observable wave inter-
ference?
A. Young's two slit experiment on gamma rays
B. Incandescent headlights of a distant car
C. Two identical antennas coherently radiating at different amplitudes
D. Monochromatic waves with a $60^\circ$ phase shift
30. A-path na pagpipilian. Two coherent light sources of
wavelength $\lambda$ are shown in the figure. If constructive in-
terference is observed a distance 5.50$\lambda$ away from source
A in the +x-axis, which of the following is a possible sep-
aration length of the two sources?
A. 3.00$\lambda$
B. 2.25$\lambda$
C. 1.50$\lambda$
D. 0.75$\lambda$