(a)i State the condition for a charged particle to experience a force in magnetic field
(ii) State the expression for the magnetic force, F acting on a charged particle, Q in a magnetic field of flux density, \(\beta\) with speed, V
(iii) Prove quantitatively that there is no magnetic force moving along the direction of a magnetic field.
(b)i Mention the main parts of an electrical transformer.
(ii) Explain how an alternating potential difference applied to the primary coil gives rise to an induced e.m.f in the secondary coil of a transformer.
(c) Proton of mass 1.7 x 10(^{-27}\) kg enters a magnetic field of flux density 0.207 normally and followed a quarter circle path before existing with a constant speed of 4.5 x 10\(^6\)m/s
(i) Explain why the speed of the proton remains constant.
(ii) Calculate the
I. radius of the circular path
II. time taken by the proton to move through the magnetic field [e = 1.6 x 10\(^{-19}\) C, \(\pi\) = 3.14]
(a) Mention three facts about photoelectric effect
(b) An electric magnetic radiation source of power 6 x 10\(^{-3}\) W emits 1 x 10\(^{16}\) photons per second. The most energetic photo electron ejected from a metal surface is stopped by a potential difference of 2.2V. Calculate the work function of the metal. [ mass of (photon) electrons 9.1 x 10\(^{-31}\) kg, e = 1.6 x 10\(^{-19}\) C]
(c) State two factors on which the activity of a radioactive sample depends
(d) Cobalt-60 source has an activity of 2.0 x 10\(^6\) Bq and a half-life of 1.8 x 10\(^8\)s. Calculate the number of radioisotope nuclei in the source.
(a) You are provided a retort stand, a spring balance, masses, a beaker containing water, another beaker containing a liquid labelled, L, and other necessary apparatus.
(i) Suspend the mass, m = 20 g on the spring balance and measure the weight in air, W\(_A\) in Newton.
(ii) Immerse the suspended mass completely in water and measure weight in water, W\(_W\) in Newton. Evaluate U\(_1\) = W\(_A\) - W\(_W\).
(iii) Immerse the suspended mass completely in the liquid L of the same volume with water and measure the weight in liquid W\(_L\). Evaluate U\(_2\) = W\(_A\) - W\(_L\).
(iv) Repeat the procedure for m = 40g, 60g, 80g, and 100g respectively. In each case, evaluate \(W_A\), W\(_W\), U\(_1\), W\(_L\), U\(_2\).
(v) Tabulate the readings.
(vi) Plot a graph of U\(_1\) on the vertical axis and U\(_2\) on the horizontal axis starting both axes from the origin (0, 0).
(vii) Determine the slope s of the graph
(viii) Evaluate K = \(\frac{1}{\text{s}}\)
(ix) State two precautions taken to ensure accurate results.
b(i) State the Archimedes' principle,
(ii) State two differences between density and relative density
(a) You are provided with two resistance wires labelled: A and B, standard resistor, R\(_x\) = 1 \(\Omega\), metre bridge, cell of emf,E, Rheostat R\(_h\), galvanometer and apparatus as shown.
Use the circuit diagram above as a guide to perform the experiment.
(i) Connect R\(_x\) in the left-hand gap of the metre bridge, a length L = 100 cm of the wire in the right-hand gap and the other apparatus shown.
(ii) Determine and record the balance point P on the metre bridge wire NQ
(iii) Measure and record L\(_x\) = NP and L\(_y\) = PQ
(iv) Evaluate R\(_1\) = \(\frac{L_y}{L_x}R_x\)
(v) Repeat the procedure for four other values of L = 90cm, 80cm, 70cm, and 60cm. In each case, determine and record the balance point, P and evaluate R\(_1\)
(vi) Repeat the experiment with the second wire B. Obtain the balance point P and evaluate R\(_2\) in each case
(vii) Tabulate the readings
(viii) Plot a graph of R\(_2\) on the vertical axis and R\(_1\) on the horizontal axis
(ix) Determine the slope, s, of the graph
(x) Evaluate K = \(\sqrt{s}\)
(xi) State two precautions taken to ensure accurate results.
b(i) State two advantages of potentiometer over voltmeter for measuring potential difference
(ii) Define internal resistance of a cell.
ALTERNATIVE B
(a) You are provided with a variable DC power supply E, a key, an ammeter, a voltmeter and other necessary materials
(i) Set up a circuit as shown in the diagram above with E = 3.0V
(ii) Close the key.
(iii) Record the voltmeter reading, V
(iv) Read the corresponding ammeter reading, I
(v) Evaluate V\(^{-1}\) and I\(^{-1}\)
(vi) Repeat the procedure for the four other values of E = 4.5V, 6.0V, 7.5V and 9.0V.
(vii) Tabulate your readings.
(viii) Plot a graph with I\(^{-1}\) on the vertical axis and V\(^{-1}\) on the horizontal axis starting with both axes from the origin. (0, 0)
(ix) Determine the slope, s of the graph.
(x) Also, determine the intercept, c on the vertical axis
(xi) What does the slope, s represent?
(xii) State two precautions taken to ensure accurate results.
(b) State two methods by which an electric current can be produced
(i) State Ohm's law.
