Contents

Pre lab 8

Here are some help for Pre lab 8!

Part 1

Tip

Look back at Lab 6!

  • The magnetic field model is similar (not the same) in many aspects to the Electric Field Model.

  • Now, given a magnet with North and South pole, could you guess what setup it resembles in Electric Field Model?

  • Then, where do the Magnetic Field lines start? Where do they end?

Caution

There are rules with drawing magnetic field lines that you should take into consideration. E.g. lines do not touch.

Part 2

  • This is just a restatement of the Right Hand Rule For Solenoids.

  • Don’t forget to tell me which finger indicates the direction of current and which indicates magnetic field.

Tip

If words are not enough for you, please feel free to visualize it with a drawing.

Part 3

  • Galvanometer is a device. A device’s name ending with meter is usually the one to measure a quantity.

  • The question now is what galvanometer measures?

Tip

What is the general name of the device to measure that quantity that you just found out?

Part 4

  • Use the right hand rules for this part!

  • Remember which finger is assigned to which quantities!

Caution

The right hand rule works a little different for moving negative charge!

Part 5

  • For this question, you need to look at the dependencies of \(B\).

  • That means you need look at the formula for \(B\) and see if any changes of the component terms affect \(B\) as described.

Part 6

  • Given 2 important pieces of information:

    • Objects are moving charged particles.

    • Both enter the same magnetic field perpendicular to their velocity.

  • With knowledge of mechanical physics, we know force causes acceleration and change in motion.

  • Why is it important? Two of your objects changes direction in opposite way after entering magnetic field. That means each experienced a force that is opposite in direction to each other.

  • Now, ask yourself: Why the force exerted on each object is opposite in direction?.

  • Here is a visualization for you:

../../_images/part6_prelab8.png

Fig. 37 Behavior of opposite charges in magnetic field

Tip

Look at the formula for magnetic force on moving charge: \(\vec{F} = q \vec{v}\times\vec{B}\).

Part 7

  • Follow the below formula (for solenoid) for this calculation:

\[B = \mu_0 n I\]

Caution

n is the number of turns per unit of length! Read carefully what you are given!

Lab 8