3/15/2012

P30 Unit B: Forces and Fields The Left Hand RULES!

1. The diagrams below show a compass at various positions around a current carrying wire. Draw the direction the compass needle would point in each diagram.

2. In the diagram below left, given the direction of the current, draw the direction of the B⃑-field at A, B and C.

3. Using the diagram above right, fill in the blanks with the letter/word that makes the sentence true.a) The direction of the B⃑-field due to the magnets is from letter ___ to ___.b) If current flows from E to F, the direction of the B⃑-field due to the wire is _______________. (clockwise/counterclockwise)c) If current flows from E to F, the direction of the magnetic force on the wire is towards letter ___.

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Name: _________

Date: _________

3/15/2012

4. In the diagram below, current is moving through a wire into the plane of the page. Draw the direction of the magnetic force acting on the wire.

5. The diagram below left shows the direction of the B⃑-field produced by an electron travelling through space. Draw in the direction of the electron’s velocity.

6. The diagram above right shows a conducting wire traveling through a region containing a B⃑-field. Draw in the direction of current flow induced through the wire.

7. The diagram below left shows an electron entering a B⃑-field. Draw in i) the path of the electron ii) the direction of the magnetic force acting on the electron in four different positions and iii) the direction of the velocity of the electron in four different positions.

8. In the diagram above right a positive aluminum ion enters the B⃑-field between two bar magnets. Which letter, X or Y, will the ion move towards?

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3/15/2012

9. The diagram below left shows the top half of a current carrying wire loop moving through a piece of cardboard. Draw in the direction of the B⃑-fields around the loop of wire and through the centre of the loop.

10. The diagram above right shows a circuit for a lifting electromagnet. Label the poles of each electromagnet when the switch is closed.

11. The diagram below left shows a current carrying wire moving through a B⃑-field. Draw in the direction of the magnetic force acting on the wire.

12. The diagram above right shows a loud speaker. The speaker consists of several parts: a strong permanent magnet in the shape of a letter “E” with two south poles at the top and bottom and a north pole in the middle, as shown, and a voice coil attached to the paper speaker cone. The voice coil is a coil of conducting wire with a current passing through it as shown. The voice coil and cone are free to move towards or away from the magnet.

Draw in the direction of the force acting on the voice coil and cone below.13. The diagram below shows a positive particle entering a region of perpendicular electric and magnetic fields. The electric field is produced by the two parallel plates as shown. Ignoring the force of gravity, if the particle is to travel through the fields undeflected:

a) Draw in the direction of the electric and magnetic forces acting on the particle.

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3/15/2012

b) Label the plates as either positive or negative.

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