Flashcards
electric fields
Cards in this deck (30)
- 1The formula for charge?charge(Q)= current(I) x time
- 2what is the difference between insulators and conductors?conductors contain free electrons and insulators dont contain free electrons.
- 3define line of force/ field lines?the direction of a line of force or field line indicates the direction of the force. Electric field line is the path followed by a free positive test charge.
- 4how to charge a metal?it must be isolated from the earth. otherwise, any charge given to it is neutralised by electrons transferring between the conductor and the earth. then the isolated conductor can be charged by direct contact with any charged object. if an isolated conductor is charged positively and then earthed, electrons transfer from the earth to the conductor to neutralise it.
- 5define electric field strength (E)?at a point in the field is defined as the force per unit charge on a positive test charge placed at that point.
- 6which direction does the force on a small charge in an electric field act if the charge is positive or negative?The force acts in the same direction to the electric field if the charge is positive.
the force acts in the opposite direction to the electric field if the charge is negative - 7Is the electric field strength a scalar or a vector?Vector
- 8Why does the charge of a test charge need to be less than one coulomb of charge?because this amount of charge would affect the charges that cause the field, and so it would alter the electric field strength.
- 9formula for electric field when there are plates involved?E= voltage(v) / Distance between the plates (D)
- 10can you derive the formula E=v/dF=QE
WORK DONE= FORCE X d
WORK DONE= Q X E X d
V=WORK DONE / Q
V= E X d
E= V X d - 11define electric potential?at a certain position in an electric field is defined as the work per unit positive charge on a positive test charge (i.e. a small charged object) when it moves from infinity to that position.
- 12formula and units for electric potentialV( electric potential)= Ep (electric potential energy ) / Q (charge)
units are V or JC^-1 - 13define equipotentiala line or surface in a field along which the electric or gravitational potential is constant. no work is done by the electric field on the test charge because the force due to the field is at right angle to the equipotential.
- 14define potential gradientAt a point in a field is the change of potential per unit change of distance along the field line at that point.
The potential gradient = - the electric field strength at any point. - 15what can you tell me about the potential gradient in a uniform field?The potential gradient is:
*constant. elecric potential is proportional to the distance.
*it makes the electric potential increase in the direction proportional to the electric field.
*equal to the opposite polarity of the electric field strength. - 16draw fields lines for both positive and negative charges.The field lines should go away from the positive charge.
The field lines should go towards the charge. - 17formula for coulombs law
- 18If the force is positive what are the charges?the charges are repulsive so they are either both positive or both negative.
- 19if the force is negative then what are the charges?the charges are attractive so the are negative and positive
- 20how do you know if the potential gradient is large?The equipotential are closer together.
- 21formula for electric field strength for radial field.
- 22when a positive test charge is put in the middle of a negative and a positive point charge what happens to the test charge and what is the electric field strength?The test charge gets attracted to the negative point charge and gets repelled by the positive point charge.
so the resultant electric field would be E1+E2=E - 23when a positively charged test charge is put in the middle of two positively charged point charges what happens to the point charge and what's the electric field strength?The test charge gets repelled by both point charges because they are the same charge.
the resultant electric field strength is
E1-E2=E - 24calculate the electric field strength when a positively charge test charge is perpendicular to both positively charged point charges?E= SQUARE ROOT E1^2 + E2^2
- 25Tell me if eletric field lines of force surrounding a point charge Q are radial or uniform.They are radial.
For negative point charges the field lines act towards the point charge.
For positive point charges the field lines act away from the point charges. - 26what is the area under an electric field strength against distance graph.the change in voltage.
- 27state in words coulombs lawforce between two (point) charges is proportional to (product of) charges
and inversely proportional to the square of their distance apart - 28electric field against distance for a repulsive charge right
- 29electric field against distance for an attractive force. remember the test charge is always positive. left
- 30graph of electric potential against distance for a uniform field
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- A level Physics (Electric Field ) Flashcards on electric fields , created by Mohamed Essa on 24/03/2017.
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- Mohamed Essa
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