Current Electricity Flashcards
(21 cards)
Charge
Charges are created due to loss/gain of electrons by a body. They are positive or negative.
Quantity of charge
Determined by the electrons in deficit or excesss
Units of charge
S.I. unit - coulomb
Smaller units - milli-coulomb, micro-coulomb, nano-coulomb
Definition of a coloumb
the charge carried by 6.25 × 10^18 electrons// a deficit of 6.25 × 10^18 electrons
Charge on one electron
1.6 × 10^-19 C
Formula for charge
Q = ne
Current
the rate of flow of charge through a conductor
Precautions for an ammeter
It should be connected in series - to be able to experience the current flow to measure it
Its positive terminal should be towards the positive terminal of the source
How is current measured?
With an ammeter
Units of current
S.I. unit - ampere (A)
weaker currents denoted by milli-ampere and micro-ampere
Definition of ampere
The current that flows through a conductor when one coulomb of charge flows through the conductor in one second.
Formula for current
I = Q/t or I = ne/t
current in electrolytes
I = n1q1 + n2q2
_________
t
Electric Potential
at a point, it is the amount of work done per unit charge in moving a test positive charge from infinity to the given point
Potential Difference
Between two points, it is the work done per charge in moving a positive test charge from one point to another
It is a scalar quantity
How is potential difference measured?
With a voltmeter
Precautions for voltmeter
It should be connected in parallel
The positive terminal of the voltmeter should be connected to the higher potential point
Unit of potential difference
S.I. unit - volt (V)
Definition of 1 volt
The potential difference at a point when 1J of work is done in moving a charge of 1 C from infinity to that point (potential)//one point to another (potential difference)
Formula for potential difference
V = W/Q
Resistance
The obstruction offered to the flow of current by the conductor.
