. Microwave ovens can have cold spots and hot spots, due to standing electromagn

Question

. Microwave ovens can have cold spots and hot spots, due to standing electromagnetic waves. This is analogous to the nodes in the standing waves in a string.

     (a) The longer the distance between cold spots:

            (i) The higher the frequency

            (ii) The lower the frequency

            (iii) The frequency is independent of this distance

     (b) In your microwave oven, the cold spots (nodes) occur every 5.0 cm, and in your neighbor’s microwave oven they occur every 6.0 cm. Which oven produces waves at a higher frequency, and by how much?

Explanation / Answer

F = C/lambda, lambda is double the size of distance between cold and hot spots,

hence f increase with the sitance dcrease and vice versa

Ans: lower the frequency.

wavelegnth of my oven=2*5= 10cm = 0.1m
lambda*frequency equals c = 3x10^8 m/s so frequency = 3x10^8/0.1 =3x10^9 = 3 GH

wavelegnth of my neighboursoven=2*5= 12cm = 0.12m
lambda*frequency equals c = 3x10^8 m/s so frequency = 3x10^8/0.12 =2.5x10^9 = 2.5 GH

Mine is higher by (3-2.5)/2.5*100=20%

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