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Figure 5 shows a solenoid - AQA - GCSE Physics - Question 4 - 2019 - Paper 1
Question 4
Figure 5 shows a solenoid. Draw the magnetic field of the solenoid on Figure 5. Figure 6 shows two iron rods placed inside a solenoid. Explain why the iron rods m... show full transcript
Worked Solution & Example Answer:Figure 5 shows a solenoid - AQA - GCSE Physics - Question 4 - 2019 - Paper 1
Step 1
Draw the magnetic field of the solenoid on Figure 5.
Answer
To illustrate the magnetic field of the solenoid, you should draw field lines that enter through one end of the solenoid and exit through the other end. The lines should be dense inside the solenoid, indicating a strong magnetic field, and should show arrows pointing in the direction from the North to the South pole.
Step 2
Explain why the iron rods move apart when the switch is closed.
Answer
When the switch is closed, an electric current flows through the solenoid, generating a magnetic field. The iron rods become temporarily magnetized due to this magnetic field. As they are magnetized, both rods align in the same direction, causing them to repel each other. The repulsive force pushes the rods apart.
Step 3
Explain why the method used by the student is not valid for this investigation.
Answer
The student's method of measuring the strength of the electromagnet by the maximum weight it could hold is flawed because it changes two independent variables (current and number of turns) at the same time. This makes it difficult to isolate the effect of each variable on the electromagnetic strength, thereby compromising the validity of the results. A more systematic approach would involve changing only one variable at a time while keeping the other constant.