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# Magnetism

Question | Answer |
---|---|

What is a magnetic field? | A region in space where magnetic forces can be felt |

What is a magnetic field line? | A line drawn in a magnetic field so that the tangent to it at any point shows the direction of a magnetic field at that point |

How does an electric current cause a magnetic effect? | Every current carrying conductor has a magnetic field around it |

What is the right hand grip rule? | Point your right thumb in the direction of (conventional) current flow, and then curl your fingers around the wire. Your fingers now point in the same direction as the circular magnetic field around the conductor. |

What is a solenoid? | A coil whose length is much longer than its radius |

What is an electromagnet? | A soft iron core wrapped in a solenoid with current flowing through it |

What is the angle between true north and magnetic north at any point on earth called? | Magnetic declination/variation |

What are electromagnets used for? | Hard disk drives . peakers, motors. Generators. MRI machines. Lifting scrap iron. |

What direction is magnetic force always acting? | Perpendicular current. Perpendicular to the magnetic field. |

When won't a current carrying conductor not experience a force? | When it is parallel to the magnetic force |

What devices work on the principle of magnetic force on a current carrying conductor? | D.C. electric motor. Moving coil loud speaker. Moving coil galvanometer. Moving coil voltmeter. Moving coil Ohmmeter. |

What does fleming's left hand rule state? | When you point your index finger in the direction of a magnetic field your thumb points in the direction of magnetic force and your middle finger points in the direction of the current |

What three factors affect the strength of the current in a magnetic field? | Current. Length of the conductor. Strength of the magnetic field |

What is magnetic flux density? | Magnetic flux density is defined as the amount of magnetic flux in an area taken perpendicular to the magnetic flux's direction. |

What direction does magnetic flux density act in? | The direction of the force on a north pole placed at that point |

What is the equation for force on a current carrying conductor? | F=ILB |

What is the unit of magnetic flux density? | The Tesla |

What is 1 Tesla? | The magnetic flux density at a point if a conductor of length 1m carrying a current of 1A experience a force of 1 N when placed perpendicular to the magnetic field |

What is the formula for the force on a moving particle? | F=qvB |

What happens to a charged particle moving at a constant speed when it enters a magnetic field and moves at right angles to the field? | It moves in a circle |

How is F=qvB derived? | qnvt/t=qnv=I Force per unit length=qnvlB F=qvB |