The purpose of this blog is to help grade 12 physics students with problems and concerns in their course. Students should also reflect on the day's lesson - question, think, get curious!

Wednesday, May 23, 2007

Magnetic force and magnetic field

Ms. Kozoriz is not in class today..so wild cats are everywhere! But Mr. Newman substitute for her on that day!!

Good day everyone..RICARDO is your scribe for today.

First thing he did is... he handed us back the the experiments and assignments.

Then we answer the no. 4 question

(a) Fg and Fe

(b) positive

(c) mg = Eq

q = mg/E

= 1.6 x 10^-18

(d) q = Ne¯

N = q/e¯

= 10e¯

CATHODE RAY TUBE

Electrons leave the cathode and accelerates toward the anodes (p. 536)

The electric field, E, alone produces a force on the electrons Fe = qE causing the electrons to deflect up to x.

The magnetic field, B, alone produces a force on the electrons FB = Bqv causing the electrons to deflect down to y.

(1) To find speed, v, of electrons, adjust B and E until electrons hit point Z

FB = FE

Bqv = qE

v= E/B

(2) To find mass, turn off E. B will deflect electrons to y where

FB = FC

Bqv = mv²/R

m = BqR/v

(3) To find the charge / mass ratio

q/m = v/BR

or

v = E/B

therefore

q/m = E/B²R

In the end of the class..he let us work on questions 8 - 16 in Moving Charges worksheet.

GOOD LUCK to our test on FRIDAY!!!

The next scribe will be...Ms. Makintosh

1 comment:

Ms K said...

What are "wild cats"??