Question 1)
a) A stationary U
92238 nucleus decays to form a Th
90234 nucleus, write a decay equation for this nuclear reaction. [2 marks]
b) The mass of the U
92238 nucleus is 4.0×10
-25kg. After the decay the thorium nucleus has a velocity of 2.4×10
5ms
-1, calculate the kinetic energy in MeV of the alpha particle produced in this decay. [4 marks]
c) Show that when a U
92238 nucleus decays to a Pb
82206 nucleus 14 particles are emitted. [3 marks]
Question 2)
a) The electric force experienced by current carrying electrons in a hall probe balances the magnetic force. V = p.d. induced across opposite faces of probe, a = separation of faces, B = magnetic flux density, v = mean drift velocity of electrons.
Show that V=Bva [3 marks]
b) Given that for the hall probe
number density = ... m
-3 current = ... A
a = ... m
b = ... m
calculate the mean drift velocity. [2 marks]
c) Given that B=0.08T calculate V [2 marks]
d) A student wants to measure the magnetic flux density between two poles of a horseshoe magnet. It is in the range 0.02-0.04T. Why is the hall probe not suitable for taking this measurement? [1 mark]
e) Explain how you would carry out a suitable experiment to measure the magnetic flux density using a current carrying wire. [4 marks]
Question 3)
a) A capacitor circuit so that a capacitor can be charged and then discharged through a resistor. The resistance of the resistor is varied. The p.d. across the capacitor is measured after it has been discharging for 15 seconds. Show that the magnitude of the gradient of a graph of ln(V) against 1/R is 15/C. [2 marks]
b) Complete a table of results by calculating ln(V) and its uncertainty for V= 3.0 +-0.2 [1 mark]
c) Complete graph by plotting 2 missing points and error bars [1 mark]
d) Use the graph to calculate the capacitance giving the uncertainty [4 marks]
Question 4)
a) You are given an ammeter, a 6V supply, a 100Ω resistor and an unlabelled box containing the resistor arrangement below. Describe how you would find out which terminals of the box are A, B, C and D and how you would find the resistances of the two resistors. Include a circuit diagram. [6 marks]
b) You are given a potential divider circuit diagram with an LDR and resistor of unknown resistance, and a graph of LDR resistance against light intensity.
Draw the circuit symbol for an LDR. [1 mark]
c) An electric switch connected across the LDR will close when the p.d. is ... V and open when it is ... V. It closes when the light intensity is 0.80 Wm
-2. Calculate the resistance of the resistor. [3 marks]
d) Calculate the light intensity when the switch opens. [3 marks]
Question 5)
a) A speaker emits sound of frequency ... kHz, and amplitude ... m The speed of sound in air is 320ms
-1. Draw a graph of displacement of air molecules against distance from speaker and label the axes. Mark a point X on the graph where molecules have maximum speed and a point Y where they have the same speed in the opposite direction. [4 marks]
b) Calculate the maximum velocity of air molecules. [2 marks]
c) Calculate c
rms of oxygen at ...
oC given that its molar mass is ... kgmol
-1. [3 marks]
d) The speed of sound can be calculated using two methods a) and b). Only one measurement is taken for each method. Method a) has a microphone and speaker fixed and another speaker moving away. Method b) has two fixed speakers and a microphone moving between them. Explain how the speed of sound can be calculated using each method, and how you would decrease the uncertainty in your calculation. [6 marks]
Question 6)
[13 marks]
Please vote to say how many marks you think you got, and reply with corrections for my answers.