1 An electric current is the overall movement of charged particles in one direction. 2  To obtain an electric current, there needs to be a continuous circuit from one terminal of a battery to the other. 3  An electric current in a circuit transfers energy from the battery to the circuit components.
A pea gravel walkway or patio costs about $5 per square foot, installed, including a layer of base rock. If you'd like to install it yourself, it will cost half as much.Add in the cost of a header or Bender Board. A wood header is about $5 per linear foot; a metal header is $6 (black metal disappears well).You won't need a header if you're installing gravel against a house, fence, or raised bed.dd in the cost of a header or Bender Board. A wood header is about $5 per linear foot; a metal header is $6 (black metal disappears well). You won't need a header if you're installing gravel against a house, fence, or raised bed.
The cost of gravel is generally $0.79 per square foot. Calculate the amount of gravel that will be needed and then contact local quarries for pricing. Remember to add in the delivery fees for the gravel. The cost of a concrete slab will vary depending upon the size of the slab as well as the thickness.he cost of gravel is generally $0.79 per square foot. Calculate the amount of gravel that will be needed and then contact local quarries for pricing. Remember to add in the delivery fees for the gravel. The cost of a concrete slab will vary depending upon the size of the slab as well as the thickness.