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Flashcards in 物理定义 Deck (13)
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1

Electric current

Electric current is the rate of flow of electric charge past a point.

2

P.d

Energy transferred per unit charge.

3

e.m.f

The total work done when unit charge goes around a complete circuit.

4

Electric field strength

The electric field strength at a point is the force per unit exert on a stationary positive charge at that point.

5

Ohm's law

For a metallic conductor at constant temperature, the current in the conductor is directly proportional to the potential difference across its ends.

6

Kirchhoff's first law

The sum of the currents entering any point in a circuit is equal to the sum of the currents leaving that same point.

7

Kirchhoff's second law

The sum of the e.m.f.s around any loop in a circuit is equal to the sum of the sum of the p.d.s around.

8

Internal resistance

The resistance of an e.m.f source.

9

Radian

An alternative unit for measuring angles.

10

Centripetal force

The net force acting on an object moving in a circle;it is always directly towards the centre of the circle.

11

The gravitational strength

The gravitational strength at a point is the gravitational force exert per unit mass on a small object at that point.

12

Gravitational potential

The gravitational potential at a point is the work done in bringing unit mass from infinity to the point.

13

Electric potential

The electric potential at a point is equal to the work done oin bringing unit positive charge from infinity to that point.