Question 1
AIM: To verify the relationship between current and voltage at constant resistance.
- (a)Connect the circuit diagram as shown in figure 1.
- (b)Ask the supervisor to check the circuit connection.
- (c)Copy Table 1 in the answer booklet.
Table 1
Voltage(V) |
Current (A) |
Resistance (W) = V/I |
0 |
|
|
2 |
|
|
4 |
|
|
6 |
|
|
8 |
|
|
10 |
|
|
- (d)Switch on the variac.
- (e)Set the variac to 0V
- (f)Read and record the ammeter readings in Table 1.
- (g) Increase the variac voltage in steps of 2V up to 10V and record the corresponding ammeter readings in Table 1.
- (h)Switch off the variac.
- (i)Complete Table 1.
- (j)Plot a graph of voltage (V) on the vertical axis against current (A) on the horizontal axis.
- (k)Determine the slope of the graph.
- Comment on the graph.
Observation
The expected answers were:
(a) Circuit connection
(b) Correct current entry
(c) Correct resistance entry
(d) correct axes
(e) reasonable scale
(f) Plotting of points
(g) Line of best fit
(h) Calculation of slope
(i) Graph comment
Table 1
Voltage (V) |
Current (A) |
Resistance |
0 |
0 |
0 |
2 |
0.1 |
20 |
4 |
0.2 |
20 |
6 |
0.3 |
20 |
8 |
0.4 |
20 |
10 |
0.5 |
20 |
The candidates did well in carrying out the instructions. The circuit was connected. Readings were taken and recorded. Graph was plotted. A good understanding of slope was displayed and majority of them got the answer right. Their comments as required indicates their understanding on the aim of the experiment. Those who did not perform well were those who did not obtain the accurate values of the current. A few were noticed to display low ability in graph plotting .