Standing Waves or Stationary Waves

Q1.

Below is a diagram of a microwave oven.

(a) Mario wants to use the stationary waves formed in the microwave oven to measure the frequency of the microwaves emitted by the transmitter.

Suggest how stationary waves are formed in the microwave oven.

[2 marks]

(b) Mario removes the turntable and places a bar of chocolate on the floor of the oven. He then switches the oven on for about one minute.

When the chocolate is removed he observes that there are three small patches of melted chocolate with unmelted chocolate between them.

Here is a diagram of the chocolate bar:

(i) Suggest why the chocolate only melts in the positions shown.

[2 marks]

(ii) Calculate the frequency of the microwaves used by the oven.

[5 marks]

[1 mark]

(Total 10 marks)