A student has a bar magnet, a piece of iron the same size as the magnet, and some paper clips - Edexcel - GCSE Physics - Question 5 - 2018 - Paper 1

The student can measure the initial length of the spring before switching on the current. Once the current is activated, the student can observe how far the iron nail moves, indicating the force of attraction. To quantify this, the student should use an ammeter to measure the current flowing through the solenoid and record its value. The student can then calculate the extension of the spring, which correlates to the force. By varying the current and repeating the experiment, the relationship between current size and force of attraction can be established.

To calculate the energy transferred in extending the spring, we can use the formula for elastic potential energy:

$E = \frac{1}{2} k x^2$

Where:

• $k = 24 \text{ N/m}$ (spring constant)
• $x = 0.12 \text{ m}$ (extension in meters)

Substituting the values:

$E = \frac{1}{2} \times 24 \times (0.12)^2 = 0.17 \text{ J}$

Thus, the energy transferred in extending the spring by 12 cm is approximately 0.17 Joules.