Explain what is happening off camera to create what you see in the video below.

St. Mary's Physics YouTube Channel


When current is on,   electromagnet's N pole attracts the S pole of compass. When current
is reversed, poles
are reversed.





Electric Bell

Name the major parts of an electric bell.

What is the function of part C?

Electric Bell

Source: Elroy M. Avery School Physics (New York: Sheldon and Company, 1895) 556

Copyright: 2009, Florida Center for Instructional Technology. See license.

| Clipart ETC | Alternate Sizes |




E - Electromagnet, H - Striker, P - Switch

C - When the striker is attracted to the electromagnet, the circuit is opened and the striker returns to its initial position





Click on the picture below
to activate a larger version of this animation

Electric Bell - Flash

[ HTML5 ]

St. Mary's H.S.





Ex 4) Magnetic field around Solenoid (Electromagnet)

(conductor arranged in a coiled pattern)

North and South Pole
 at either end of the core.





1. Determine North and South pole with ...


a) North Pole of a Compass

b) 2nd Left Hand Rule

Why Left and not right?? 

Step 1 - Current travels from
 (-) to (+)  terminal


DRAW the direction of the current on the wires




Step 2 - WITH PALMS AWAY, point the fingertips of left hand in direction of current






Step 3 - Thumb - North Pole!!


North Pole - RIGHT or LEFT??? 











North Pole - Top or Bottom?










North Pole - Right or Left?










[ Flash ]






Field Strength




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