Microwaves Use High Powered Radio Waves And The Water Molecules

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Microwaves use high powered radio waves generated by a vacuum tube (also known as a magnetron) to heat up the drink and foodstuff placed within them. The high powered radio waves are channelled into the food compartment through a waveguide, and they heat up the food by interacting with the water molecules in the foodstuff. The greatest interaction between the high powered radio waves and the water molecules occur at the greatest amplitude of the waves, at points on the wave where the amplitude is equal to zero, there will be no interaction between the high powered radio waves and the water molecules, so this point is a cold spot within the microwave. The electromagnetic waves coming from the vacuum tube change direction almost 2.5 billion…show more content…
When the time is is up, immediately remove the jug from the microwave. Using the thermometer measure the new temperature of the water and record the highest temperature seen on the thermometer. Repeat steps 1 to 5 for 200 ml of water. Repeat steps 1 to 5 for 300 ml of water. Repeat steps 1 to 5 for 400 ml of water. Repeat steps 1 to 8 for 120 seconds. Repeat steps 1 to 8 for 180 seconds. Data The table below shows the data that was collected. Mass of Water (g) Initial Temperature (oC) Final Temperature (oC) Temperature Difference (oC) Time (seconds) Time (seconds) Time (seconds) 60 120 180 60 120 180 60 120 180 100 20 17 19 68 93 89 28 76 70 200 13 14 13 42 71 94 29 57 81 300 13 13 13 34 54 73 21 41 60 400 13 14 13 29 50 60 16 36 47 In order to calculate the total energy input from the microwave to the water, we use this equation: Q = mc ΔT Then we divide our answers by the amount of seconds the water was left in the microwave for. When we know the rate of energy input into the water we can then work out the total energy efficiency by dividing the energy transferred into the water by the total amount of energy the microwave draws from the socket. The energy input from the socket to the microwave used, is 1000 watts Q = the heat energy transferred - in Joules (J) m = the mass of water used, (1 ml of water = 1 g of water) - in grams (g) c = the specific heat capacity of water (this is 4181 J / Kg oC) ΔT = change in the temperature of the water

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