Unit 3B: gravitational, electric & magnetic fields

Question 1

Oil Drop Experiment

Answer 1

• consited of using an atomizer to sray a fine mist of oil droplets between two oppositley charged parallel plates
• the oil droplets picked up charge due to friction
• the charge on the parallel plates created an electric field
• by ajusting the electric field Milikan was able to balance the downward force of gravity and the upward electric force
• the mass of the oil droplets was deteremined by the final speed of the oil droplets as they fell after the electric field was turned off

Question 2

Properties of Magnetic Field

Answer 2

1. Field lines travel out of north into south
2. Field lines are parallel, so the never cross
3. Field line are concentrated at poles of the magnet
4. Field line are continous with no origin point and are created by dipoles

Question 3

How was Earth’s magnetic field created

Answer 3

• the dipoles created deep within the Earth act like a giant EM magnet because the flow of molten metals below the surface
• the turning motion material produces a charge flow similar to the current passing through a wire to produce a magnetic field

Question 4

Maxwell’s Equations of Electromagnetism

Answer 4

1. The distrubution of electric charges in space is determined by the electric field that the charges produce
2. Magnetic and electric field lines are similar except for the fact that magnetic field lines are continous; they do not begin or end the way electric field lines do on charges. Magnetic field line are dipolar
3. Electric fields are created by changing the magnetic field
4. Magnetic fields are created by changing electric fields or by moving electric charges

Question 5

Compare and contrast gravitational, electric and magnetic fields or forces

Answer 5

• Gravitational field acts on all mass and energy
• Electric field acts only on charged particles
• Magnetic field acts only on moving charged particles