Magnetism - Science Doctor - Free Printable

Here is the step-by-step solution to the problems on the worksheet.

Basic Section

* Q1: Magnetism acts over a distance without touching.
* *Answer:* non-contact
* Q2: The standard unit for measuring force is named after Isaac Newton.
* *Answer:* Newton (N)
* Q3: This is the fundamental rule of magnetism. Same poles push away, different poles pull together.
* *Answer:* repel, attract
* Q4: The three main elements that are magnetic are Iron, Nickel, and Cobalt.
* *Answer:* Iron, Nickel, Cobalt
* Q5: The diagram shows a simple rectangular magnet.
* *Answer:* Bar magnet
* Q6: The lines represent the magnetic field.
* *Answer:* Magnetic field lines (or Flux lines)
* Q7: The arrows on the magnetic field lines always point away from the North pole and towards the South pole. In the diagram, the arrows point to the right. Therefore, the left side is North and the right side is South.
* *Answer:* Left end = N, Right end = S

Medium Section

* Q8:
* a) False (it is a non-contact force).
* b) False (Opposites attract).
* c) True (Opposites attract).
* d) False (Likes repel).
* e) True (Opposites attract).
* Q9: The magnetic field is strongest where the lines are closest together. In the diagram, the lines are bunched tightly at the ends of the magnet.
* *Answer:* At the poles (the ends). We can tell because the magnetic field lines are closest together there.
* Q10: A permanent magnet creates its own magnetic field constantly.
* *Answer:* A magnet that produces its own magnetic field all the time.
* Q11: An induced magnet becomes magnetic only when placed inside a magnetic field.
* *Answer:* A material that becomes a magnet only when placed in a magnetic field.
* Q12: Induced magnetism always results in attraction.
* *Answer:* Attraction
* Q13: The filings align with the magnetic field lines.
* *Answer:* They arrange themselves along the magnetic field lines.

Hard Section

* Q14:
* Look at the top diagram: Magnet 1 (AB) attracts Magnet 2 (CD).
* Look at the bottom diagram: Magnet 1 (AB) repels Magnet 3 (EF).
* Logic: Only two magnets can repel each other. If an object attracts another object, it could be a magnet or just unmagnetized iron (because magnets attract iron). However, if object A repels object B, both A and B *must* be magnets.
* Since Magnet 1 repels Magnet 3, Magnet 1 is definitely a magnet.
* Since Magnet 1 attracts Magnet 2, Magnet 2 could be a magnet (opposite poles) or unmagnetized iron.
* Conclusion: Bar 2 (CD) is the piece of unmagnetized iron. We know this because it is attracted to a magnet but never shown to repel one.
* Q15: (Sketching descriptions)
* a) Two North poles: The lines come out of both poles and curve away from each other, leaving a gap in the middle where they don't touch (a neutral point).
* b) Two South poles: The lines go into both poles and curve away from each other, leaving a gap in the middle.
* c) North and South: The lines come out of the North pole and go directly into the South pole, connecting the two.
* Q16:
* a) Similarities: Both are non-contact forces. Both get weaker as objects get further apart. Differences: Gravity only attracts (pulls). Magnetism can attract or repel. Gravity affects all mass; magnetism only affects magnetic materials.
* b) Similarities: Both are non-contact forces. Both can attract or repel. Differences: Magnetism affects magnetic materials (iron, etc.). Electrostatic forces affect charged objects. Magnetism has North/South poles; Electrostatics has Positive/Negative charges.

Final Answer:
Basic
Q1. non-contact
Q2. Newton (N)
Q3. repel, attract
Q4. Iron, Nickel, Cobalt
Q5. Bar magnet
Q6. Magnetic field lines
Q7. Left side: N, Right side: S

Medium
Q8. a) False, b) False, c) True, d) False, e) True
Q9. At the poles (ends). The lines are closest together there.
Q10. A magnet that keeps its magnetism all the time.
Q11. A material that acts like a magnet only when inside a magnetic field.
Q12. Attraction
Q13. They line up to show the shape of the magnetic field.

Hard
Q14. Bar 2 (CD) is the unmagnetized iron.
*Reasoning:* Magnetism can only push (repel) another magnet. It can pull (attract) either another magnet or unmagnetized iron. Since Bar 1 pushes Bar 3 away, Bar 1 must be a magnet. Since Bar 1 pulls Bar 2, Bar 2 could be a magnet or just iron. Because Bar 2 is never shown to push Bar 1 away, it is the unmagnetized iron.

Q15. (Sketch descriptions)
a) Lines curve away from each other with a gap in the middle.
b) Lines curve away from each other with a gap in the middle.
c) Lines connect the North pole to the South pole.

Q16.
a) Similarities: Both are non-contact and get weaker with distance. Difference: Gravity only attracts; Magnetism attracts and repels.
b) Similarities: Both are non-contact and can attract or repel. Difference: Magnetism acts on magnetic materials (N/S poles); Electrostatics acts on electric charges (+/-).