Instructor: Dr. Bruce Law, CW
327, Tel: 532-1618.
Home Work 21
REVIEW QUESTIONS – Chap 24
R24.4. The rule for interaction between
magnetic poles is similar to the rule for interaction between electrically
charged particles, namely, like poles repel whereas unlike poles attract. For
charged particles, like charges repel whereas unlike charges attract.
R24.5. Magnetic poles are very different
than electric charges in that magnetic poles always come in pairs i.e. every N
pole will always have an associated S pole. By contrast electric charges do not
necessary come in pairs i.e. you can find a single positive or negative electric
R24.7. A magnetic field is produced by
moving electric charges eg. an
electric current in a circuit or an electron moving around the nucleus of an
R24.10. In an unmagnetized
iron nail the magnetic domains are randomly oriented. In a magnetized iron
nail, the magnetic domains point in the same direction.
EXCERCISES – Chap 24
E24.3. Attraction will occur because the
magnet induces opposite polarity in a nearby piece of iron. North will induce south, and south will induce north. This is similar to
electrical charge induction, where a balloon will stick to a wall whether the
balloon is negatively or positively charged.
E24.21. Moving electrons are deflected from
their paths by a magnetic field. A magnet held in front of a TV picture
deflects the electron beam from its intended path and distorts the picture.
E24.23. Yes, it does. Since the magnet
exerts a force on the wire, the wire, according to Newton`s
third law, must exert an equal and opposite force on the magnet.
REVIEW QUESTIONS – Chap 25
R25.3. The magnetic
field must change with time in order to get electromagnetic induction in a
EXCERCISES – Chap 25
E25.11. There is no fundamental difference between an electric motor and an
electric generator. When mechanical energy is put into the device and
electricity is produced, we call it a generator. When electrical energy is put
in and it spins and does mechanical work, we call it a motor.