The Earth's gravitational force pulls objects towards the centre of the Earth.
"Down" is towards the centre of the Earth, wherever you are on the planet
Earth’s gravitational force makes the ball move down towards the centre of the Earth.
Sun’s gravitational force makes the Earth move in an orbit around the Sun.
An electric field shows us how electric charges behave around each other.
See what elec field looks like: http://www.colorado.edu/physics/2000/waves_particles/wavpart3.html
Positive and negative charges attract each other.
What do two positive charges do to each other?
Lightning discharges an excess of positive and negative charge within clouds, between clouds, or between clouds and the ground.
Read p78-79 – Gravity
Try questions 4 & 5 on p81.
Read p139/140 and try questions.