O Level Physics 5054 Paper 41, May/June 2026

Figure 1.1 represents a piece of modelling clay in the shape of a cylinder of length $l$. Two points, A and B, are marked on the modelling clay as shown in Figure 1.1. Measure length $l$ in cm to the nearest mm. $l=\text{.................................................... cm}$

Figure 1.1 is drawn to one-half full size. Calculate the actual length $L$ of the cylinder. $L=\text{.................................................... cm}$

Two blocks are placed around the cylinder of modelling clay so that point A is between them as shown in Figure 1.2. The distance $d_1$ between the two blocks is the diameter of the modelling clay at point A. Figure 1.2 is drawn full size. Measure $d_1$ in cm to the nearest mm. $d_1=\text{.................................................... cm}$

The blocks are moved so that point B on the modelling clay is between them. Figure 1.3 shows the modelling clay in the new position. Figure 1.3 is shown full size. Measure $d_2$ in cm to the nearest mm. $d_2=\text{.................................................... cm}$

The average diameter $d$ of the modelling clay is given by the equation shown. $$d=\frac{d_1+d_2}{2}$$ Use your values from 1(a)(iii) and 1(a)(iv) to find $d$. Give your answer in cm to the nearest mm. $d=\text{.................................................... cm}$

The cylinder is placed on a top pan balance as shown in Figure 1.4. Record the mass $m$ of the modelling clay to the nearest gram. $m=\text{.......................................................g}$

The density of the modelling clay is calculated using the equation shown. $$\text{density}=1.27\times \frac{m}{d^{2}L}$$ Use your answers in 1(a)(ii), 1(a)(v) and 1(b) to calculate the density of the modelling clay. Give your answer to three significant figures, and state the unit of your answer. $$\text{density}=\text{.................................. unit ...............}$$

Suggest why it is important to take measurements of the diameter at more than one place along the length of the cylinder.

Some of the apparatus used is shown in Figure 2.1. Draw a diagram of the circuit shown in Figure 2.1, using standard electrical symbols.

Add a voltmeter to the circuit diagram you have drawn to measure the potential difference across the $470\mathrm{\Omega }$ resistor.

The switch is closed. Figure 2.2 shows the reading on the voltmeter. Record the potential difference $V_R$ across the fixed resistor. $V_R=\text{...................................................... V}$

The student: • opens the switch • disconnects the voltmeter from across the fixed resistor • connects the voltmeter across the thermistor • closes the switch and reads the voltmeter • opens the switch. The potential difference $V_T$ across the thermistor is recorded as $2.2\text{ V}$. The resistance $R_T$ of the thermistor is calculated using the equation shown. $$R_T=\frac{470\times V_T}{V_R}$$ Calculate $R_T$. $R_T=\text{...................................................... }\mathrm{\Omega }$

Calculate the current $I$ in the circuit using the equation shown. $$I=\frac{V_R+V_T}{470+R_T}$$ $I=\text{.......................................................A}$

The thermistor is now immersed in a beaker of iced water as shown in Figure 2.3. The student measures $V_R$ and $V_T$ with the thermistor immersed in the beaker of iced water. The new values for $V_R$ and $V_T$ are shown. $V_R=1.7\text{ V}$ $V_T=2.8\text{ V}$ Using the equation in 2(a)(iv), calculate the resistance $R_T$ of the thermistor when the thermistor is immersed in iced water. $R_T=\text{...................................................... }\mathrm{\Omega }$

Describe how the resistance of the thermistor changes as its temperature changes.

A student says that the current in the circuit when the thermistor is in iced water is the same as the current in the circuit when the thermistor is at room temperature. State why this is incorrect by referring to the equation $V=IR$.

Suggest a possible value for the resistance of the thermistor when it is placed in water heated to $50{}^{\circ }\text{C}$.

The student places a thermometer in a clamp as shown in Figure 3.1. Record the temperature on the thermometer to the nearest $0.5{}^{\circ }\text{C}$. This is room temperature ${\theta }_R$. ${\theta }_R={\text{..................................................... }}^{\circ }\text{C}$

Explain how the student avoids parallax error when reading the room temperature from the thermometer scale.

procedure The student: • places the glass beaker below the thermometer • lowers the thermometer so that the bulb is in the middle of the beaker as shown in Figure 3.2 • adds $100{\text{ cm}}^3$ of hot water to the beaker • waits for the thermometer to reach its maximum value and then starts the stopwatch. Readings of the temperature ${\theta }_1$ of the water are recorded every $1.0\text{ minute}$ for $6.0\text{ minutes}$. The student gently stirs the water before taking each reading. The readings are recorded in Table 3.1 on page 10. Suggest why it is important to stir the water before taking each reading.

The student: • pours away the water in the beaker • covers the sides and the bottom of the beaker with aluminium foil • repeats the procedure in the first part of 3(b) to obtain readings of temperature ${\theta }_2$ of the water in the beaker covered in aluminium foil. The student also records the new readings in Table 3.1. One reading was omitted in error. Complete Table 3.1 with a suggested value for the missing temperature at $2.0\text{ minutes}$.

On the grid provided in Figure 3.3, plot a graph of ${\theta }_1{\mathrm{/}}^{\circ }\text{C}$ on the $y$-axis against $\text{time}\mathrm{/}\text{min}$ on the $x$-axis. Start your $x$-axis at 0. You do not have to start your $y$-axis at 0. Draw the curve of best fit for the ${\theta }_1$ results. Label this line ${\theta }_1$.

On the same axes in Figure 3.3, plot a graph of ${\theta }_2{\mathrm{/}}^{\circ }\text{C}$ on the $y$-axis against $\text{time}\mathrm{/}\text{min}$ on the $x$-axis. Draw the curve of best fit for the ${\theta }_2$ results. Label this line ${\theta }_2$.

Use the data in Table 3.1 and your graphs in Figure 3.3 to compare the rates of cooling of the water in the beakers without and with the aluminium foil.

Explain why the thermometer bulb is placed in the middle of the beaker.

State two factors that are controlled in this experiment to ensure that a valid comparison can be made. factor 1 .............................................................................................................................. factor 2 ..............................................................................................................................

Other than adding insulation to the beaker, suggest a change to the apparatus that will decrease the rate of cooling of the water.