Current electricity

Question 1

Define electric current.

Answer 1

Electric current is the flow rate of electric charge through a conductor or any cross-sectional area.
I = Q/t
SI unit: Ampere (C/s)
​When the current is not steady,
The current at time t across the cross-section of the conductor is defined as the ratio of ∆Q to ∆t in the limit of ∆t tending to zero,
I= 𝐥𝐢𝐦 ∆Q/∆t =ⅆ𝐐/ⅆt
𝚫𝐭→𝟎

Question 2

State Ohm’s law and derive its formula

Answer 2

It is a basic law regarding the flow of currents that was discovered by G.S. Ohm in
1828.
At constant temperature, the current flowing through a conductor is directly proportional to the potential difference between the ends of the
conductor.
V∝I
V=RI
The constant of proportionality R is called the resistance of the conductor.
The SI unit of resistance is the ohm and is denoted by the symbol Ω.

Question 3

Explain drift velocity.

Answer 3

The average velocity attained by electrons in a conductor due to an electric field is called the Drift velocity. The force acting on the electron due to the electric field,
F=qE=−eE
The acceleration of the electron,
a=F m =−eE m
If t is the time between two successive collisions,
v = at
Then the velocity gained by an electron,
v = −eEt m
Drift velocity,
vd=−eE m (t)average
—-> 𝐯ⅆ=−𝐞𝐄 𝐦 𝛕