Questions:
620. Lever arm length
625. Amplification factor
630. Impedance matching
635. Pressure
640. Theory of hearing

 
620. A lever is used to lift a 50 N weight with application of a 5 N force. The arm to which the 5 N force is applied is 1 m long; what is the length of the other arm?

a) 1 m
b) 1/10 m
c) 10 m
d) 0.5 m

Fundamentals of Sound reference: Sec. 12-B.
 

625. What is the amplification factor of the lever in Question 620?

a) 5
b) 10
c) 1/10
d) none of these

Fundamentals of Sound reference: Sec. 12-B.
 
 
 

630. A megaphone amplifies one's speaking voice. One way it does this is by acting as an impedance matching device, in analogy with the role played by the middle ear in hearing. Can you explain how this might work in this case?

Check your answer here.

Fundamentals of Sound reference: Sec. 12-B.
 

635. A Hindu fakir lays on a bed of nails. If any nail exerts a pressure greater than 5x106 N/m², it will puncture his skin. He weighs 700 N and the area of a nail point is 2x10^-7 m². How many nails must the bed have if he is to avoid skin punctures.

a) 10
b) 200
c) 300
d) 500
e) 700

Fundamentals of Sound reference: Sec. 12-B.
 
 

640. The microphone of an old-style telephone contained a metal plate that simply vibrated as a unit at the frequency of the speaker? (it had a very broad frequency response curve which meant it vibrated with roughtly the same amplitude at any frequency.) This plate's vibration modulated an electric current that carried the signal on the telephone lines. This type of signal transformation is most analogous to which of the posssible theories of the inner ear?

a) place theory
b) volley theory
c) traveling wave theory
d) None of these.

Fundamentals of Sound reference: Sec. 12-C.
 
 

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