part a : electric current Flashcards
What is direct current?
Direct current is a current of constant magnitude flowing in one direction.
What are the characteristics of a primary cell?
- Chemical reaction is irreversible
- Chemical energy is converted into electrical energy when current is drawn
- Cannot be recharged
- Internal resistance is high
- Capable of giving weak current only
- Light and cheap
- Examples: Simple cell, Daniell cell
What are the characteristics of a secondary cell?
- Chemical reaction is reversible
- Electrical energy is converted into chemical energy when current is passed
- Can be recharged
- Internal resistance is low
- Can provide low as well as high current
- Heavy and costly
- Examples: Lead-acid, Nickel-iron, Lithium-ion
What is current?
Current is the rate of flow of charge across a cross-section normal to the direction of flow of current.
What happens when two charged bodies are joined by a metallic wire?
Electrons flow from the body having more electrons to the body having fewer electrons.
Is current a scalar of vector quantity
scalar
What is the formula for current (I)?
q divided by t
How is one ampere (A) defined?
One ampere (A) is equal to one coulomb per second.
What is the conversion for one milliampere (mA)?
One milliampere (mA) = 10^(-3) A
What is the conversion for one microampere (μA)?
One microampere (μA) = 10^(-6) A
difference between electronic current and convectional current
the rate of flow of electrons in a direction is called electronic current in that direction
convectional current is in a direction opp to the motion of electrons
what do you mean by one ampere if current flows through a circuit
it means that 6.25 x 10^18 e pass in one second across that cross section of the conductor
value of charge an electron carries
1.6 x 10^-19 coulomb
