No questions found
(a) Assemble the apparatus as shown in Fig. 1.1 with the total mass $m$ of the mass hanger and mass equal to 150g.
The distance between the bottom of the split cork and the bottom of the mass hanger should be 64 cm. It may be necessary for the mass to hang over the edge of the bench.
(b) (i) Move the mass a short distance to one side and then carefully release it so that it swings with as little bouncing as possible, as shown in Fig. 1.2.
(ii) Take measurements to determine the period $T$ of the pendulum. [2]
(c) Change $m$ and repeat (b) until you have six sets of values of $m$ and $T$. Do not adjust the string in the split cork.
Record your results in a table. Include values of $T^2$ in your table. [10]
(d) (i) Plot a graph of $T^2$ on the $y$-axis against $m$ on the $x$-axis. [3]
(ii) Draw the straight line of best fit. [1]
(iii) Determine the gradient and $y$-intercept of this line. [2]
(e) It is suggested that the quantities $T$ and $m$ are related by the equation
$$T^2 = am + b$$
where $a$ and $b$ are constants.
Use your answers from (d)(iii) to determine the values of $a$ and $b$. Give appropriate units. [2]
588
541
525
In this experiment, you will investigate an optical system.
(a) (i) Use a small piece of Plasticine to fix the torch horizontally on one of the wooden blocks.
(ii) Put the remaining Plasticine inside the transparent container and push the lens into it so that the lens is held vertically and parallel to two opposite sides of the container.
(b) (i) Position the apparatus as shown in Fig. 2.1, with the front of the torch approximately 32 cm from the lens.
(ii) Switch on the torch.
(iii) Measure the distance $u$ from the front of the torch to the centre of the lens, as shown in Fig. 2.2. [1]
(iv) Place the white screen as shown in Fig. 2.2. Keeping the screen vertical, move it until it shows a sharp image of the LEDs in the torch.
(v) Measure the distance $v$ from the centre of the lens to the screen, as shown in Fig. 2.2. [1]
(c) Estimate the percentage uncertainty in your value of $v$. [1]
(d) Calculate the value of $f$ using the expression $f = \frac{uv}{(u + v)}$. [1]
(e) (i) Without moving the container and the torch, pour water into the container to submerge the lens.
(ii) Reposition the screen so that it shows a sharp image of the LEDs.
(iii) Measure the new distance $v_w$ from the lens to the screen. [2]
(iv) Calculate $f_w$ using $f_w = \frac{uv_w}{(u + v_w)}$.
$f_w = \text{..................................................}$
(v) Switch off the torch.
(f) Justify the number of significant figures you have given for your value of $f_w$. [1]
(g) (i) Pour the water from the container back into the beaker, making sure that the lens remains fixed in the container.
(ii) Repeat (b), (d) and (e) but with the front of the torch approximately 22 cm from the lens. [3]
(h) It is suggested that the relationship between $f_w$ and $f$ is $f_w = kf$ where $k$ is a constant.
(i) Using your data from (d) and (e)(iv) and your data from (g), calculate two values of $k$. [1]
(ii) Explain whether your results support the suggested relationship. [1]
(i) (i) Describe four sources of uncertainty or limitations of the procedure for this experiment. [4]
(ii) Describe four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures. [4]
593
538
595
