(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\(_h\), ...
Question 1 Report
(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.
Answer Details
(vii)
| L(cm) | L\(_x\)(cm) | L\(_y\)(cm) | R\(_1\) = (\(\frac{L_y}{L_x})R_x\)\(\Omega\) |
L\(_{x2}\) | L\(_{y2}\) | R\(_2\) = \(\frac{L_{y2}}{L_{x2}}R_x\)\(\Omega\) |
| 100.0 | 5.2 | 94.8 | 18.2 | 21.5 | 78.5 | 3.6 |
| 90.0 | 6.0 | 94.0 | 15.7 | 22.5 | 77.5 | 3.4 |
| 80.0 | 6.8 | 93.2 | 13.7 | 23.4 | 76.6 | 3.3 |
| 70.0 | 7.6 | 92.4 | 12.2 | 24.5 | 75.5 | 3.1 |
| 60.0 | 8.4 | 91.6 | 10.9 | 25.6 | 74.4 | 2.9 |
(viii) SEE THE GRAPH ABOVE
(ix) Slope = \(\frac{Δ R_2}{Δ R_1}\) = \(\frac{3.5 - 3.3}{17.0 - 14.6}\) = \(\frac{0.2}{2.4}\) = 0.083
(x) K = \(\sqrt{0.083}\) = 0.2881
(xi) I Tight connection/clean terminal was ensured II. Key removed when readings were not being taken.
b(i) I. A potentiometer can be used for measuring the internal resistance of a cell and also to compare the e.m.f. of two cells. II. A potentiometer gives the exact value of potential difference across any two points in a circuit.
(ii) It refers to the opposition to the flow of current offered by the cells and batteries themselves resulting in the generation of heat.
Download The App On Google Playstore
Everything you need to excel in your exams
