Solutions to SQA examination

1994 Higher Grade Physics

Paper I Solutions

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1. D		11. D			21. D
2. B		12. C			22. A
3. C		13. C			23. B
4. C		14. B			24. E
5. C		15. D			25. B
6. A		16. C			26. C
7. D		17. A			27. A
8. D		18. B			28. D
9. D		19. A			29. D
10.E		20. A			30. E


	The displacement(s) is equal to the total area(A1+A1) under
	the graph.

	s = A1+A1
	s = ut +(v-u)t/2

	Note that from the definition of acceleration :

	a = (v-u)/t
	=>(v-u)= at

	Substitute this into the expression above.

	s = ut + att/2
	s = ut + at2/2 as required.

32.	Density of  air = Mass of air released/Volume of air released
		r = Mair/Vair

	Mair = (363.86-362.00)g = 1.86g = 1.86x10-3kg
	Vair = 1687.00cm3 = 1687.00x10-6m3

		r = 1.86x10-3kg/1687.00x10-6m3
		r = 1.1025kg/m3

33.a.	T(K) = T(oC) + 273
	T(K) = -196 + 273
	T(K) = 77K

   b.	The kelvin temperature is directly proportional to the kinetic
	energy of particles. At 0K particles have no kinetic energy. A lower
	energy state/temperature, is therefore, not possible. 

34.a.	Vinverting input = 0V

   b.	I = V/R
	V = 0.5V
	R = 10,000W

	I = 0.5/10000
	I = 50mA

35.	l = v/f
	l = 340/1000
	l = 0.34m

	Path difference = (1.37-1.20)m = 0.17m

	This means that loudspeaker 2 is a distance of 0.17m further away
	from the microphone than loudspeaker 1. This is a distance equivalent
	to l/2. Therefore, the waves reach the microphone 180o out of phase 
	and interfere destructively, reducing the amplitude of the sound.

36.a.	All metals and carbon are conductors.
	Plastic and rubber are examples of insulators.
	Group IV elements such as silicon are semiconductors.

   b.	By adding pentavalent (group V) atoms to group IV semiconductor, n-type 
	semiconductor material is made. This material has a lower resistance than 
	pure semiconductor, as a result of an excess of negative charge carriers 
	in the structure.

37.a.	When two atoms join, or fuse together, to produce a single atom of greater mass
	the reaction is called fusion.

   b. 	The mass of the product of a fusion reaction is less than that of the
	initial reactants. This "missing mass" is converted into energy.

	E = mc2

	Where:	m = missing mass
		c = speed of light


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