Which one of the following statements is not correct?

Asked in UPSC CAPF 2016 · Topic: Electric Current (Electrical Power and Energy, Joule heating effect)

1. The earth’s magnetic field is due to the motion of metals like iron and nickel in the core of the earth
2. The magnetic field lines of force are widely separated near the poles of a magnet but these lines come closer to one another at other places
3. If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density decreases
4. When the speed of a conductor moving through a magnetic field is increased, the induced voltage increases

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