You are provided with a resistance box R, voltmeter, key, cell of e.m.f. E, constantan wire, standard resistor, RX, an ammeter, and other necessary apparatus. (i) Measure and record the e.m.f. E of the cell provided. (ii) Set up the circuit as shown in the diagram above. (iii) Set R to 1\(\Omega\). Close the key, read and record the current I and the corresponding voltage V. (iv) Repeat the procedure for four other values of R= 2\(\Omega\), 4\(\Omega, 6\(\Omega\), and 8\(\Omega\). (v) In each case, read and record I and V. (vi) Tabulate the reading. (vii) Plot a graph of V on the vertical axis and I on the horizontal axis. (viii) Determine the slope s, of the graph. (ix) State two precautions are taken to ensure accurate results (b) )State two advantages of connecting identical cells in parallel. (ii) State two factors to consider in choosing the material for the design of a resistor
Explanation
R(n)
I(A)
V(v)
1.02.04.06.08.0
0.400.350.280.220.18
0.650.580.220.450.40
E = 3.00v
(x) Precautions: - Key opened in between readings/key opened when readings were not taken - Ensuring tight connections Avoid parallax error when taking a reading on voltmeter/ammeter Repeated readings (shown on the table) - Noted/corrected zero error on voltmetre/ammeter - Clean terminals ensured (b)Advantages of connecting identical cells in parallel produce a larger amount of current. supply steady current for a long period - efficiency is high (ii) Factors to consider in choosing a material for the design of a resistor - Power rating-Tolerance - Voltage rating -Temperature coefficient - Noise - Frequency response - Stability - Resistivity