LESSON 4
Current, Resistance, and
Electromotive Force
,CURRENT
, What is an electric current?
As a physical quantity, current is Electric current (I) consists of
the rate at which charge flows charges in motion
past a point on a circuit. from one area to another.
DIRECTION OF
ELECTRIC CURRENT
Current is a rate quantity and is expressed mathematically as
𝑸
𝑰=
𝒕
where Q is the amount of charge passing through a
given area in time t.
The SI unit of current is the ampere (A), an 1 ampere is defined to
𝟏𝑪
be one coulomb per second 𝟏𝑨 = .
𝟏𝒔
, Compute the current involved when a truck batter sets in motion
with a charge of 720 C in 4.00 s while starting the engine.
Solution:
Step 1: Identify the given values. Step 3: Calculate the unknown using
the known values.
Q = 720 C 𝑸
𝑰=
t = 4.00 s 𝒕
𝟕𝟐𝟎 𝑪
=
Step 2: Identify the unknown. 𝟒. 𝟎𝟎 𝒔
Electric Current, I 𝑪
= 𝟏𝟖𝟎
𝒔
𝑰 = 𝟏𝟖𝟎 𝑨
Current, Resistance, and
Electromotive Force
,CURRENT
, What is an electric current?
As a physical quantity, current is Electric current (I) consists of
the rate at which charge flows charges in motion
past a point on a circuit. from one area to another.
DIRECTION OF
ELECTRIC CURRENT
Current is a rate quantity and is expressed mathematically as
𝑸
𝑰=
𝒕
where Q is the amount of charge passing through a
given area in time t.
The SI unit of current is the ampere (A), an 1 ampere is defined to
𝟏𝑪
be one coulomb per second 𝟏𝑨 = .
𝟏𝒔
, Compute the current involved when a truck batter sets in motion
with a charge of 720 C in 4.00 s while starting the engine.
Solution:
Step 1: Identify the given values. Step 3: Calculate the unknown using
the known values.
Q = 720 C 𝑸
𝑰=
t = 4.00 s 𝒕
𝟕𝟐𝟎 𝑪
=
Step 2: Identify the unknown. 𝟒. 𝟎𝟎 𝒔
Electric Current, I 𝑪
= 𝟏𝟖𝟎
𝒔
𝑰 = 𝟏𝟖𝟎 𝑨
