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20 questions
Can you produce current in a wire with a magnet that is sitting still?
Yes; having a magnet near a wire is enough to excite the electrons
No; the magnetic field has to be changing to excite the electrons
No; magnets cannot create electricity
A coil spins in a magnetic field. Of the following
which causes an increase in the induced EMF in
the coil?
Spinning the coil faster
Removing the coil from the magnetic field
Keeping the flux at a constant rate
Decreasing the number of turns of wire in
the coil
Magnetic flux is related to magnetic field strength by the formula
Φ=BA
Φ=BA2
Φ=B/A
Φ=B/A2
When a charged particle moving with velocity v enters a magnetic field at right angles it will be forced into a circular path with radius r given by
mv/Bq
Bq/mv
mv2/Bq
none of these
The size of the force exerted on a moving charge relative to an external magnetic field is given by
Bqv
Bqvcosθ
Bqvsinθ
none of these
A uniform magnetic field of strength 4 mT is used to deflect a beam of electrons into a circular path of diameter 65 mm. Calculate the speed of the electrons
2.3x107ms-1
4.6x107ms-1
3.0x107ms-1
2.0x107ms-1
What does the direction of the pointing fingers mean in this picture?
the direction of the voltage
the rotation of the wire
the direction of the magnetic field
the direction of the current
F = BIL If the current and magnetic field are doubled, the magnetic force on the wire
halves
remains the same
doubles
quadruples
F = qvB If the speed and charge double, what happens to the magnetic force?
halves
remains the same
doubles
quadruples
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