Electric Fields Flashcards
What is the definition of Electric Field Strength?
Electric Field Strength is defined as the force per unit positive charge.
How can conducting paper be used to map out electric field lines?
- Positive charge and negative charge on either end of paper
- Voltmeter then used to measure pd at different points on paper
- Points with same voltage can be joined up to show equipotential lines which are always perpendicular to field lines
How can an electrolytic tank be used to map out electric field lines?
- Tank of water with positive and negative ions dissolved in it
- Electrodes put in water to create positive charge on one side of tank and negative on other
- Voltmeter then used to find points within water where pd is the same
- Equipotentials and field lines can then be mapped out
How can a uniform electric field be created?
By connecting two parallel plates to the opposite poles of a battery.
Do field lines go from positive to negative or from negative to positive?
From positive to negative.
What is electric potential?
The electric potential energy that a unit positive charge (+1C) would have at a point in an electric field.
What does the sign (+/-) of absolute electric potential V depend on?
It depends on the charge Q. V is positive when Q is positive and the force is repulsive and vice versa.
What is the gradient of an electric potential - distance from charge graph equal to?
The field strength at the point of the gradient.
What is electric potential difference?
If two points in an electric field have different absolute electric potential, then there is an electric potential difference between them - it is the energy needed to move a unit charge between these two points.
What is the area under an electric field strength - radial distance graph?
The electric potential difference between two points.
What do the letters mean in the equation ΔW = QΔV?
ΔW - Work done in moving a charge in J
Q - the charge being moved in C
ΔV - electric potential difference in V
What can ΔW also be written as?
Force x distance.
What is the main difference between Gravitational fields and electric fields?
Gravitational forces always attract, whereas electrostatic forces can be attractive or repulsive.
