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AP® Physics 1 & 2

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Moderate

Microwave Oven

APPH12-VMCWRU

Students look up the specifications of a microwave oven and discover that the frequency of the electromagnetic radiation is $2450\text{ MHz}$.

The note on the inside of the microwave states that it operates at $1250\text{ Watts}$. They measure the oven and find that the interior dimensions are $45$ centimeters by $45$ centimeters by $27$ centimeters.

Which statement below best represents the wavelength of the microwaves and gives a brief explanation?

A

The wavelength of the microwaves is approximately $9\text{ centimeters}$. The dimensions of the oven are even multiples of this wavelength so standing waves are created.

B

The wavelength of the microwaves is approximately $18\text{ centimeters}$. The dimensions of the oven are even multiples of half of this wavelength so standing waves are created as the wave reflect with a node on each end.

C

The wavelength is approximately $1.6\times { 10 }^{ -28 }\text{ meters}$ which is derived from the energy of the microwave using the relationship $E=\cfrac { hc }{ \lambda } $.

D

The wavelength of the microwaves is approximately $12\text{ centimeters}$ which is derived from the wave equation and the frequency of the microwaves.