Home / iGCSE Physics (0625) 4.1 Simple phenomena of magnetism Paper 4 -Exam Style Questions

iGCSE Physics (0625) 4.1 Simple phenomena of magnetism Paper 4 -Exam Style Questions- New Syllabus

iGCSE Physics (0625) Extended - All Topics

Question

(a) State what is meant by a magnetic field.
(b) Fig. 8.1 shows an ammeter connected to a coil wound on a thin plastic cylinder. A small trolley is placed on a curved track which passes through the cylinder.
The trolley is released from the position shown in Fig. 8.1. It travels through the coil from right to left. The trolley travels back from left to right. It has a lower maximum speed when it travels from left to right.
The plastic cylinder does not affect any magnetic field. A magnet is fixed to the trolley.
(i) State why there is a lower maximum speed when the trolley travels back from left to right.
(ii) Fig. 8.2 shows a close-up view of the ammeter.
As the trolley enters the coil moving from right to left, the ammeter needle deflects to the left and then returns to zero.
State and explain any changes to the deflection on the ammeter as the trolley enters the coil when moving back from left to right.

Most-appropriate topic codes (Cambridge IGCSE Physics 0625):

• Topic $4.1$ — Simple phenomena of magnetism (Part $\mathrm{(a)}$)
• Topic $4.5.1$ — Electromagnetic induction (Part $\mathrm{(b)(ii)}$)
• Topic $1.5.1$ — Effects of forces (Part $\mathrm{(b)(i)}$)

▶️ Answer/Explanation

(a)
For the correct answer:
A region in which a magnetic pole experiences a force.

A magnetic field is defined as a volume of space surrounding a magnet or a current-carrying conductor where magnetic materials or poles experience a non-contact force.

(b)(i)
For the correct answer:
Energy is lost due to friction or work done against the induced magnetic field.

Friction between the trolley and the track dissipates energy as heat. Additionally, by Lenz’s Law, the induced current creates a magnetic field that opposes the motion, acting as a braking force.

(b)(ii)
For the correct answer:
The deflection is still to the left, but the magnitude is smaller.

The same pole enters from the opposite side moving in the opposite direction, which maintains the same current direction. However, the lower speed $v$ reduces the rate of change of magnetic flux linkage $\frac{\Delta \Phi}{\Delta t}$, resulting in a smaller induced e.m.f. and current.

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