28/03/2020Magnetism and Electromagnetic Effects(Senior Class Physics Study by Topics) 0Comments by Gate Academy Welcome to your Magnetism and Electromagnetic Effects(Senior Class Physics Study by Topics) NAME EMAIL PHONE NUMBER 1. Ampere-turn is the unit of magneto-motive force (mmf). False True2. An advantage of an electromagnet over a permanent magnet is the fact that An electromagnet requires no power source. An electromagnet can be switched on and off. An electromagnet does not have specific polarity. Permanent magnets must always be cylindrical, but electromagnets can have any shape3. A particle that does not carry an electrical charge is a: Atom Neutron Proton Electron4. A substance with high retentivity Can make a good ac electromagnet. Is always a diamagnetic material. Is well suited to making a permanent magnet. Repels both north and south magnetic poles.5. What substance is attracted to a magnet? Iron Silver Water Lead6. A bar magnet is divided in two pieces. Which of the following statements is true about the force between the broken pieces if they face each other with a small separation? There is an electric repulsive force between the broken pieces. There is a magnetic attractive force between the broken pieces. There is an electric attractive force between the broken pieces. There is a magnetic repulsive force between the broken pieces.7. The magnetic flux around a straight, current-carrying wire Does not vary in strength with distance from the wire. Is strongest near the wire. Consists of straight lines parallel to the wire. Gets stronger with increasing distance from the wire.8. If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity Less than that of disc and in the same direction Equal to that of disc and in the opposite direction Less than that of disc but in opposite direction Equal to that of disc and in the same direction9. A vertical wire carries an electric current into the page. What is the direction of the magnetic field at point P located to the south from the wire? South East West. North.10. Geomagnetic lines of flux Are never horizontal, no matter where you go. Are vertical at the geomagnetic equator. Are perfectly symmetrical around the earth, even far out in space. Are horizontal at the geomagnetic equator.11. Which of the following is not a unit of flux? All of the above Tesla Maxwell Weber12. A permeable substance is one Which is a strong magnet Which is a good conductor Through which the magnetic lines of force can pass very easily Which is a bad conductor13. If two magnets were in this order: NS SN they would: Attract Do nothing Repel14. Which of the following is expected to have the maximum permeability? Zinc Brass Copper Ebonite15. A current-carrying wire is placed perpendicular to the page. Determine the direction of the electric current from the direction of the magnetic field Clockwise. Into the page. Counter-clockwise. Out of the page.16. If a wire coil has 100 turns and carries 1.30 A of current, what is the magnetomotive force? 164 Gb 76.9 Gb 61.0 Gb 130 Gb17. Any magnet has two ends, each one called a: Magnetic field Magnitized material Magnetic pole None of the above18. A magnet made of a material that keeps its magnetism is known as a Lifetime magnet Energizer bunny magnet Temporary magnet Permanent magnet19. An ac electromagnet Attracts pure, unmagnetized iron. Attracts only permanent magnets. Repels all permanent magnets. Either attracts or repels permanent magnets, depending on the polarity.20. The smallest particle of an element is known as an: Proton Electron Atom Neutron21. A material that can be permanently magnetized is generally said to be Ferromagnetic. Electromagnetic. Diamagnetic. Ultramagnetic.22. How can you make a magnet temporarily lose its magnetism? By blowing on it By hitting it very hard Both a & c By heating it23. A certain amount of current flows through a ring-shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil? Decreases Increases Remains same First increases and then decreases depending on the depth of iron insertion24. An advantage of a magnetic disk, compared with magnetic tape, for data storage and retrieval is that Disks are less susceptible to magnetic fields. Disks look better. A disk lasts longer. Data can be stored and retrieved more quickly with disks than with tapes.25. A straight long wire carries an electric current to the top of the page. The current is placed in a uniform magnetic field directed out the page. What is the direction of the magnetic force on the current? Left. Right To the bottom of the page To the top of the page26 out of 25Time is Up!