Figure 7 shows a search coil positioned on the axis of an electromagnet, with the plane of the search coil perpendicular to the axis. A magnetic field is produced by a constant current in the electromagnet. Assume that the magnetic flux density inside the search coil is uniform. The distance between the search coil and the end of the electromagnet is $x$. Figure 8 shows how the magnetic flux density $B$ of the field varies with $x$. The search coil has 200 turns and a cross-sectional area of $3.5 imes 10^{-5} \, m^{2}$. 1. The search coil is placed at $x = 0.070 \, m$. Show that the magnetic flux linkage through the search coil is $4.9 imes 10^{-4} \, Wb$. 2. The search coil is now moved at a constant speed of $0.80 \, m \, s^{-1}$ along the axis so that $x$ is increasing. An emf is induced across the terminals of the search coil. 3. Explain what happens to the value of the emf as the search coil moves. 4. The search coil passes through the position where $x = 0.10 \, m$. Deduces whether the emf can exceed $5 \, V$ for values of $x$ greater than $0.10 \, m$.

Photo AI

Figure 7 shows a search coil positioned on the axis of an electromagnet, with the plane of the search coil perpendicular to the axis - AQA - A-Level Physics - Question 4 - 2021 - Paper 2

Question 4

Figure-7-shows-a-search-coil-positioned-on-the-axis-of-an-electromagnet,-with-the-plane-of-the-search-coil-perpendicular-to-the-axis-AQA-A-Level Physics-Question 4-2021-Paper 2.png

Figure 7 shows a search coil positioned on the axis of an electromagnet, with the plane of the search coil perpendicular to the axis. A magnetic field is produced by... show full transcript

Worked Solution & Example Answer:Figure 7 shows a search coil positioned on the axis of an electromagnet, with the plane of the search coil perpendicular to the axis - AQA - A-Level Physics - Question 4 - 2021 - Paper 2

Step 1

The search coil is placed at $x = 0.070 \, m$.

96%

114 rated

Answer

To find the magnetic flux linkage $\\Phi$ through the search coil, we use the formula:

\Phi = N \times A \times B

where:

$N = 200$ (number of turns)
$A = 3.5 \times 10^{-5} \, m^{2}$ (cross-sectional area)
For $x = 0.070 \, m$ , refer to Figure 8 for $B$ , which is found to be $0.005 \, T$ .

Plugging in the values:

\Phi = 200 \times 3.5 \times 10^{-5} \times 0.005 = 4.9 \times 10^{-4} \, Wb

Step 2

The search coil is now moved at a constant speed of $0.80 \, m \, s^{-1}$ along the axis so that $x$ is increasing.

99%

104 rated

Answer

As the coil moves away from the electromagnet, the distance $x$ increases. The change in distance results in a change in the magnetic flux density $B$ , resulting in the rate of change of flux linkage, $rac{d\Phi}{dt}$ , which induces an emf according to Faraday's law:

\text{emf} = -\frac{d\Phi}{dt}

Thus, as the search coil continues to move, the flux linkage decreases, inducing an emf that varies depending on the rate of change of flux.

Step 3

The search coil passes through the position where $x = 0.10 \, m$.

96%

101 rated

Answer

At this position, we need to assess the magnetic flux density $B$ again from Figure 8. We establish whether the induced emf can be greater than $5 \, V$ . The emf can be calculated using the relationship from Faraday's law, which states that the maximum induced emf arises when the rate of change of flux linkage is at its peak. If we calculate the value of $B$ at $x = 0.10 \, m$ and apply it to the formula, we can determine if emf can exceed $5 \, V$ based on the induced conditions.

97% of Students

Report Improved Results

98% of Students

Recommend to friends

100,000+

Students Supported

1 Million+

Questions answered

Figure 7 shows a search coil positioned on the axis of an electromagnet, with the plane of the search coil perpendicular to the axis - AQA - A-Level Physics - Question 4 - 2021 - Paper 2

Worked Solution & Example Answer:Figure 7 shows a search coil positioned on the axis of an electromagnet, with the plane of the search coil perpendicular to the axis - AQA - A-Level Physics - Question 4 - 2021 - Paper 2

The search coil is placed at $x = 0.070 \, m$.

The search coil is now moved at a constant speed of $0.80 \, m \, s^{-1}$ along the axis so that $x$ is increasing.

The search coil passes through the position where $x = 0.10 \, m$.

Join the A-Level students using SimpleStudy...

Other A-Level Physics topics to explore