CIE iGCSE Co-Ordinated Science P4.1 Simple phenomena of magnetism Exam Style Questions Paper 3
Question
(a) Fig. 6.1 shows a bar magnet. It is not known which end is the north pole or the south pole.
(i) A boy has a second bar magnet. He knows which end is the south pole and which end is the north pole. Describe how he can use the second magnet to determine which end is the south pole and which end is the north pole of the magnet in Fig. 6.1.
▶️Answer/Explanation
The boy can use the second magnet to determine the poles of the magnet in Fig. 6.1 by bringing the known north pole of the second magnet close to one end of the unknown magnet. If the end of the unknown magnet is attracted to the north pole of the second magnet, then that end is the south pole of the unknown magnet. Conversely, if the end of the unknown magnet is repelled by the north pole of the second magnet, then that end is the north pole of the unknown magnet. This is because like poles repel each other, and unlike poles attract each other.
(ii) Draw the pattern and direction of magnetic field lines around the bar magnet in Fig. 6.2.
▶️Answer/Explanation
The magnetic field lines around a bar magnet emerge from the north pole and enter the south pole. The lines should be drawn as continuous curves that loop from the north pole to the south pole, with arrows indicating the direction of the magnetic field (from north to south). The field lines should be closer together near the poles, indicating a stronger magnetic field in those regions.
(b) The boy hears music from a radio. The loudness of the music increases. At the same time, the music changes to a lower pitch. State how the amplitude and the frequency of the sound wave change as the loudness increases and the pitch becomes lower.
▶️Answer/Explanation
As the loudness of the music increases, the amplitude of the sound wave increases. Amplitude is directly related to the loudness of the sound. As the pitch of the music becomes lower, the frequency of the sound wave decreases. Frequency is directly related to the pitch of the sound. Therefore, an increase in loudness corresponds to an increase in amplitude, and a decrease in pitch corresponds to a decrease in frequency.
(c) The boy has healthy hearing so he can clearly hear the sounds from the radio. State the range of audible frequencies that the boy can hear.
▶️Answer/Explanation
The range of audible frequencies for a person with healthy hearing is typically from 20 Hz to 20,000 Hz (20 kHz). This range can vary slightly depending on the individual’s age and hearing health.