9.3+Electric+field,+potential+and+energy

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Electric field, potential and energy
9.3.1 Define electric potential and electric potential energy. Students should understand the scalar nature of electric potential and that the potential at infinity is taken as zero. Students should understand that the work done in moving a point charge between two points in an electric field is independent of the path taken. ELECTRIC POTENTIAL ENERGY: The energy a charge has due to its position in an electric field. This can be positive or negative; potential around a positive charge is positive since work is done to bring a positive test charge nearer. Unit: joule. ELECTRIC POTENTIAL: The energy per coulomb needed to bring a positive test charge from infinity to a point in an electric field. Zero potential is at infinity. Unit: JC-1 or volt (V).

9.3.2 State and apply the expression for electric potential due to a point charge

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SEE APPLET HERE FOR ELECTRIC FIELDS AND POTENTIAL : []

9.3.3 State and apply the formula relating electric field strength to electric potential gradient.

9.3.4 Determine the potential due to one or more point charges. Potential is a scalar quantity which is added according to scalar rules. 9.3.5 Describe and sketch the pattern of equipotential surfaces due to one and two point charges. 9.3.6 State the relation between equipotential surfaces and electric field lines. ELECTRIC POTENTIAL GRADIENT: The change in potential per metre. Electric field strength is the negative of potential gradient. r and E are in opposite directions, hence the minus sign. Measured in Vm-1.

ELECTRIC EQUIPOTENTIAL: Lines or surfaces joining points in an electric field which are at the same potential. They are perpendicular to the electric field lines

9.3.7 Solve problems involving electric potential energy and electric potential.

PRACTICAL WORK: Use the simulation at [|PHET for Charges and Fields] to plot a graph of potential against distance for small collections of charges. See the practical instructions document at the link for the details and an example.