Magnetism — Set 4
Physics · चुंबकत्व · Questions 31–40 of 50
In ordinary magnets, a single isolated magnetic pole is generally not observed because?
Correct Answer: B. Magnetic poles usually occur in pairs
A bar magnet always shows both north and south poles together. If you cut it, each piece still has two poles. This is why isolated poles are not seen in common magnets.
If a bar magnet is broken into two pieces, each piece becomes?
Correct Answer: D. A smaller magnet with both poles
Breaking a magnet produces smaller magnets, each with a north and a south pole. The domain structure forms poles at the new ends. This shows that poles are not separated by simply cutting a magnet.
Which statement about magnetic field lines is correct?
Correct Answer: C. Magnetic field lines never intersect.
Field lines cannot intersect because that would imply two directions of field at one point. At any location, the magnetic field has a single well-defined direction. Field line diagrams are a visual tool to represent that direction.
The closeness (density) of magnetic field lines in a diagram indicates?
Correct Answer: D. Strength of the magnetic field
Where field lines are closer together, the magnetic field is stronger. Where they are farther apart, the field is weaker. This is why lines crowd near the poles of a bar magnet.
Inside a bar magnet, magnetic field lines generally go from?
Correct Answer: B. South to north
Field lines form closed loops, so inside the magnet they go from south to north. Outside the magnet they return from north to south. This closed-loop idea is used in many basic magnetic diagrams.
A compass points roughly toward geographic north because near geographic north Earth behaves like a magnetic?
Correct Answer: B. South pole
The north-seeking end of a compass is attracted to a magnetic south pole. Near geographic north, Earth’s field behaves like a magnetic south pole. This is why a compass points toward geographic north in a general sense.
The angle of dip is generally zero at the?
Correct Answer: C. Magnetic equator
Dip is zero where Earth’s field is horizontal. This happens at or near the magnetic equator. At higher magnetic latitudes, the dip increases.
The angle of dip is generally about 90° at the?
Correct Answer: D. Magnetic poles
Dip becomes 90 degrees where Earth’s field is vertical. This occurs near the magnetic poles. A dip needle points straight down or up there.
The SI unit of magnetic dipole moment is?
Correct Answer: B. Ampere-meter squared
Magnetic dipole moment is measured in ampere-meter squared in SI. It equals current times area for a current loop. A larger dipole moment generally means a stronger magnet.
Magnetic flux through a flat surface is commonly given by?
Correct Answer: C. Φ = BA cosθ
The correct answer is 'Φ = BA cosθ'. Flux equals B times area times cosine of the angle between B and the area normal. This is why orientation changes the flux through the same area. Maximum flux occurs when the surface is perpendicular to the field.