No questions found
In this experiment, you will investigate changes in potential difference in a circuit as one of the resistances is varied.
(a) Assemble the circuit of Fig. 1.1.
(b) Connect the movable lead to terminal Y and record the voltmeter reading $V_0$.
(c) (i) Connect the movable lead to terminal X and leave it connected there for the rest of the experiment.
(ii) Select one of the other labelled resistors provided and connect it between the crocodile clips on the component holder. Record the resistance $R$ of your selected resistor and the voltmeter reading $V$.
(d) Repeat (c)(ii) using a different labelled resistor until you have six sets of readings of $R$ (measured in ohms) and $V$.
Disconnect the cell when you have finished your measurements.
In your table of results include columns for the values of $\frac{1}{V}$ and the values of $\frac{R}{(1000 + R)}$.
(e) (i) Plot a graph of $\frac{1}{V}$ on the $y$-axis against $\frac{R}{(1000 + R)}$ on the $x$-axis.
(ii) Draw the line of best fit.
(iii) Determine the gradient and $y$-intercept of the line of best fit.
(f) The quantities $V$ and $R$ are related by the equation
$$\frac{1}{V} = \frac{1000k}{P} \left( \frac{R}{1000 + R} \right) + k$$
where $k$ is a constant and $P$ is the resistance of resistor P.
Using your answers from (e)(iii), determine the value of $P$.
Give an appropriate unit.
595
540
504
In this experiment, you will investigate how the length of a thread of cotton affects the amount of energy it can absorb before breaking.
(a) Use the boss to clamp the nail to the retort stand at a height of about 50 cm above the bench. Place the apparatus in the tray.
(b) (i) Cut a 45 cm length of thread.
(ii) Tie the ends of the thread together to make a large loop. Suspend the loop from the nail and slot the 50 g mass into it, securing the mass with sticky tape, as shown in Fig. 2.1.
(c) (i) Measure the length $l$ as shown in Fig. 2.1.
(ii) Lift the 50 g mass vertically a distance $h$ of 5 cm, as shown in Fig. 2.2. Release the mass.
(iii) Keep repeating (c)(ii), each time increasing the value of $h$, until the thread breaks. Record the value of $h$ at which the thread breaks.
(d) Estimate the percentage uncertainty in your value of $h_{final}$.
(e) Calculate the gravitational potential energy $E_P$ given to the 50 g mass when it was lifted the distance $h_{final}$.
$E_P = mgh_{final}$ where $g = 9.81 \text{ ms}^{-2}$.
(f) Cut an 85 cm length of thread. Repeat (b)(ii), (c) and (e).
(g) It is suggested that $E_P$ and $l$ are related by the equation
$E_P = k \sqrt{l}$
where $k$ is a constant.
By calculating values of $k$, explain whether your results support this relationship.
(h) (i) State and explain four sources of error or limitations of the procedure in this experiment.
(ii) Suggest and explain four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures.
524
581
532
