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  3. question 6 1 mark explain why a mechanical wave needs...

Question: question 6 1 mark explain why a mechanical wave needs...

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Question 6 (1 mark)

Explain why a mechanical wave needs a medium to transfer energy.


Question 9 (3 marks)

To deaden pain in minor operations, a liquid that vaporises easily is sometimes sprayed onto the skin. Using thermodynamic principles, explain how this liquid cools the skin and when the effect ends.


Question 10 (4 marks)

A current-carrying wire runs horizontally across a table. The conventional current direction, I, is running from left to right. The wire produces a magnetic field of 2.8 x 10-6 T measured 15.4 cm from the wire

A. What current must the wire be carrying to produce this field? 3 Marks

B. Draw a diagram showing the direction of the magnetic field around the wire. 1 Mark


Question 11 (4 marks)

The audible range of frequency for a healthy human is from 20 Hz to 20 kHz. If the speed of sound in air is 340 m s−1 to what range of wavelengths do these frequencies correspond? 


Question 13 (4 marks)

A. Some galaxies appear to have a red shift in colour, meaning the light they produce seems redder once it reaches Earth. Making reference to the Doppler Effect and spectrum, explain why this happens and how this relates to the relative movement of these galaxies with respect to Earth. (3 Marks)


B. State why the value of vsource would be positive or negative. (1 Mark)



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