Coils "P" and "Q" each have a large number of turns of insulated wire. When switch "S" is closed, the pointer of galvanometer "G" is deflected towards the left. To make the pointer of "G" deflect toward the right one could:
Correct answer: D. Open S
- A. Move the slide of the rheostat R quickly to the right
- B. Move coil P toward coil Q
- C. Move coil Q toward coil P
- D. Open S
Explanation
When "S" is closed the magnetic flux will be in increasing order in coil Q and galvanometer shows left deflection. While when "S" is opened, the magnetic flux will be in decreasing order. So, the direction of current will be reversed (right deflection) according to Lenz's law.
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About Electromagnetism
Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
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