What do you
already know
about electricity?
In a water hose, the rate of flow of the water
through its open end can be controlled by
adjusting the faucet or by putting constrictions on
the water hose.
Due to electric potential energy, electrons move
from one point to another. Thus, electric potential
energy can be transferred to electrons through
work done. This movement is possible because of
the electric field around the negative charges.
The velocity of this motion is known as DRIFT
VELOCITY.
Normally, electrons move to any direction. If this flow is
regulated and made to move continuously in one
direction, then the flow becomes an ELECTRIC CURRENT.
As a result, the drift velocity of the moving charges all
point to a single direction along the conductor. Drift
velocity and electric current are directly proportional.
This means that a higher drift velocity results in a
higher amount of current and vice – versa.
Mathematically, electric current is computed using the equation
𝒒
𝑰=
𝒕
The symbol 𝑰 indicates the electric current, and 𝒒 is
the amount of charges that pass through a conductor for
every unit of time, 𝒕. The unit for current is coulomb
per second (C/s) or ampere A.
Sample Problem #1
Compute the current produced by a 6.5 x 10 18 C
charge flowing in 15 s.
GIVEN: 𝒒 = 𝟔. 𝟓 𝒙 𝟏𝟎𝟏𝟖 𝑪
𝒕 = 𝟏𝟓 𝒔𝒆𝒄𝒐𝒏𝒅𝒔
Sample Problem #2
A steady current of 0.6 A flows through a wire. How
much charge passes through a wire in 1 minute?
GIVEN: 𝑰 = 𝟎. 𝟔 𝑨
𝒕 = 𝟏 𝒎𝒊𝒏𝒖𝒕𝒆 𝟔𝟎 𝒔𝒆𝒄𝒐𝒏𝒅𝒔
Sample Problem #3
How much time does it take the wire to passed through a
current of 8.99 x 10 11 A with a charge of 3.5 x 10 14 C ?
GIVEN:
𝑰 = 𝟖. 𝟗𝟗 𝒙 𝟏𝟎𝟏𝟏 𝑨
𝒒 = 𝟑. 𝟓 𝒙 𝟏𝟎𝟏𝟒 𝑪
OHM’S LAW
Ohm's Law states that the
current flowing in an electric
circuit is directly proportional to
the applied voltage and
inversely proportional to the
resistance of the material.
OHM’S LAW
𝑽 = 𝑰𝑹
Where 𝑽 is the voltage, 𝑰
is the current and 𝑹 is the
resistance.
SAMPLE PROBLEM:
A 12 V battery is connected to a resistor
with a resistance of 4 Ω.
a) What is the current flowing through
the circuit?
b) If the resistor is used for 5 minutes,
how much charge passes through it?
SAMPLE PROBLEM:
A 25-volt battery is connected to a
resistor with a resistance of 6 ohms.
a) What is the electric current flowing
through the circuit?
b) If the resistor operates for 2
minutes, how much charge passes
through it?
BIG IDEA
Charges that flow easily or consistently make up
an electric current. The electric current delivers
electrical energy to appliances, making your life
more convenient.
ACTIVITY
1. Compute the current produced by a 13.6 x 10 17 C
charge flowing in 12 s.
2. How much charge passes through a steady
current wire of 18.5 x 10 15 A in 2 mins?
ACTIVITY
3. How long does it take the wire to passed through
a current of 9.35 x 10 15 A with a charge of 6.5 x
10 13 C ?
4. Compute the current produced by a 12.78 x
10 16 C charge flowing in 3mins.
