You are provided with a voltmeter V, a chemical cell/ battery E; two standard resistors R, and R a potentiometer a key K a jockey, and other necessary materials.
Set up a circuit as shown in the diagram above.
Close the key K.
Make contact with the potentiometer wire AB using the jockey at a point C such that AC = x = 20cm
Read and record the voltmeter reading
Evaluate x\(^{-1}\) and v\(^{-1}\)
Repeat the procedure for other values of x= 30, 40, 50, 60 and 80cm.
Tabulate your readings.
Plot a graph with V\(^{-1}\) on the vertical axis and x\(^{-1}\) on the horizontal axis, starting both axes from the origin (0, 0).
Determine the:
(a) slope, s, of the graph;
(b) intercept, c, on the vertical axis.
State two precautions taken to ensure accurate results.
(b)i. State the two devices in which ohm's law does not apply.
ii. A current of 1 A is supplied to two resistors of resistance 2\(\Omega\) and 3\(\Omega\) connected in parallel. Calculate the current in each resistor.
Verified Correct Answer: .
Physical Principles & Numerical Solution
x/cm
v/volt
x\(^{1}\)/cm\(^{-1}\)
v\(^{1}\)/volts\(^{-1}\)
20
0.15
0.050
6.667
30
0.20
0.033
5.000
40
0.30
0.025
3.333
50
0.40
0.020
2.500
60
0.50
0.016
2.000
80
0.60
0.013
1.667
Slope = \(\frac{6.667-1.667}{0.050-0.013} = \frac{5}{0.037}\)
= 135.135cm/volt
intercept = 0
Precautions;
- Tight connections /clean terminals was ensured
- Key removed when readings are not being taken.
- Parallex error avoided in reading voltmeter/ rule.
- Zero error noted and corrected for in the voltmeter/rule
- Dragging jockey along the wire avoided
Source: Myschool Past Questions Archive (Record #60018)