Figure 6 shows a wire in a magnetic field. The direction of the current in the wire is shown. There is a force on the wire due to the current in the magnetic field. In which direction is the force on the wire? Tick (✓) one box. Give two ways that the direction of the force on the wire could be reversed. 1 2 The length of the wire in the magnetic field is 0.050 m. The force on the wire is 0.072 N. Magnetic flux density is 360 mT. Calculate the current in the wire. Use the Physics Equations Sheet. Current = ... A Figure 7 shows a simple motor. Explain why the coil rotates when there is a current in the coil.

GCSE AQA Physics Combined Science Magnetism, Magnetic Forces & Fields: Figure 6 shows a wire in a magne

Figure 6 shows a wire in a magnetic field - AQA - GCSE Physics Combined Science - Question 4 - 2019 - Paper 2

Question 4

Figure 6 shows a wire in a magnetic field. The direction of the current in the wire is shown. There is a force on the wire due to the current in the magnetic field.... show full transcript

Worked Solution & Example Answer:Figure 6 shows a wire in a magnetic field - AQA - GCSE Physics Combined Science - Question 4 - 2019 - Paper 2

Step 1

There is a force on the wire due to the current in the magnetic field. In which direction is the force on the wire?

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Answer

The direction of the force on the wire is downward.

Step 2

Give two ways that the direction of the force on the wire could be reversed.

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Answer

Reverse the direction of the current.
Reverse the direction of the magnetic field.

Step 3

Calculate the current in the wire.

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Answer

Given:

Length of wire: $l = 0.050 \, m$
Force: $F = 0.072 \, N$
Magnetic flux density: $B = 360 \, mT = 0.360 \, T$

Using the formula for the force on a current-carrying wire: $F = BIl$ Rearranging the formula to find the current $I$ : $I = \frac{F}{Bl} = \frac{0.072}{0.360 \times 0.050} = 4.0 \, A$

Step 4

Explain why the coil rotates when there is a current in the coil.

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Answer

The coil experiences a magnetic field due to the permanent magnet and the current in the wire causes a magnetic field that interacts with the magnet. The current flows in opposite directions in each side of the coil, resulting in forces acting on opposite sides. This leads to a torque that causes rotation. The split-ring commutator ensures that the direction of current in the coil is always in the same direction relative to the magnetic field, allowing the coil to reverse its direction with each half rotation.

Figure 6 shows a wire in a magnetic field - AQA - GCSE Physics Combined Science - Question 4 - 2019 - Paper 2

Worked Solution & Example Answer:Figure 6 shows a wire in a magnetic field - AQA - GCSE Physics Combined Science - Question 4 - 2019 - Paper 2

There is a force on the wire due to the current in the magnetic field. In which direction is the force on the wire?

Give two ways that the direction of the force on the wire could be reversed.

Calculate the current in the wire.

Explain why the coil rotates when there is a current in the coil.

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