Target: 10 Questions in 10 minutes

An IB Physics data booklet is helpful

 1. Which of the following arrows correctly shows the path of a fast moving alpha particle through the charged plates shown here? The field is strongest between the plates.

2. In which direction will the wire be pushed?

• A. Downwards
• B. Upwards
• C. To the right
• D. To the left

3. The force on the wire is given by the formula F = B I L sinθ. The letter 'L' stands for....

• A. the length of the wire within the magnetic field
• B. the total length of the wire
• C. the length of the magnet
• D. the length or distance between the 2 poles of the magnets

4. An electron moves at a uniform velocity into an electric field. The field is perpendicular to the motion of the electron, and directed vertically downwards.

Whch of these sentences best describes the consequent acceleration of the electron?

• A. Accelerates upwards
• B. Accelerates downwards
• C. Accelerates parallel to the original motion
• D. Moves in a circle, accelerates towards the centre of the circle

5-7. An electron moves at a constant speed into a magnetic field as shown. (The dot/circle indicates the field is directed out of the screen).

5. In which direction will the electron be pushed as it enters the field?

• A. To the left
• B. To the right
• C. In to the screen
• D. Out of the screen

6. The experiment is repeated with a proton of the same magnitude of charge and moving at the same velocity, but with a much higher mass than the electron.

Which of these statements is true for the size of the resulting force, compared to the force on the electron?

7. Another charged particle moves upwards into the field at constant speed.

The particle will follow a circular path of radius r. Assuming the field strength and velocity stay constant, how is the charge to mass ratio (${q \over m}$) of the particle related to the radius of this circle?

• A. ${q \over m} \propto {1 \over r^2}$
• B. ${q \over m} \propto {1 \over r}$
• C. ${q \over m} \propto {r}$
• D. ${q \over m} \propto {r^2}$

8. The Earth's magnetic field is of the order of 10^-5 Tesla. To produce a force of 1 N on a wire of length 10 m (held perpendicularly to the field) the current flowing must be....

• A. 10^-6 A
• B. 10^-4 A
• C. 10 ⁴ A
• D. 10 ⁶ A

9+10: The diagram shows two parallel wires P and Q, both carrying a current I.
The distance between the wires is 2 m. Both wires experience a force F on each metre of length due to the field created by the other wire.

9. The current in both wires is doubled, and the distance reduced to 0.4 m.
The resulting force on each wire will now be:

• A. 8 F
• B. 10 F
• C. 20 F
• D. 100 F

10. Which of the following correctly describes the direction of force acting on wires P and Q?