Electric current

OBJECTIVES:At the end of the lesson, the successful students are able to:

Understand the concept of electric current;

describe the relationship of the voltage, current, and resistance using the ohm’s law;

perform the group activity in solving the problems; and

develop cooperation and participation during class activity.

OLVAGTE

VOLTAGE - the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts.

ETINSRCESA

RESISTANCE- a material’s

opposition to the flow of electric current; measured in ohms.

RUTNREC

CURRENT- a flow of

electricity through a conductor; measured in amperes.

ELECTRIC CURRENT

Baldwin B. Damonsong Jr.

Electric Current

Flow of electrons from one place to another.

Electric current means a flow of charge in the same way that water current flows.

Ohm’s Law

' :Ohm s law I V

; ; V V

I V IR RR I

Ohm’s law states that the current ( I ) through a given conductor is directly proportional to the potential difference ( V ) between its end points.

Example 1. When a 3-V battery is connected to a light, a current of 0.006 A is observed. What is the resistance of the light filament?

The SI unit for electrical resistance is the ohm, W :

1 W

Example 2.Find the current of an electrical circuit that has resistance of 50 Ohms and voltage supply of 5 Volts.

Given:V = 5VR = 50Ω

Find: I = ?

Solution:I = V / R I = 5V / 50Ω I = 0.1A

Activity:

1. Find the resistance of an electrical circuit that has voltage supply of 10 Volts and current of 0.005A.

Solution:

V = 10VI = 0.005AR = V / I = 10V / 0.005A = 2000Ω

2. What would the effect be on a person if they stuck their finger into a regular wall outlet that supplies 120V with completely dry skin (R=100,000ohms)?

Solution:

I = I = I = 0.0012 A

3. A resistance of 10 is placed across a 9 V battery. What current flows through the battery?

Solution: I = I = I = 0.9 A

4. A 110 volt wall outlet supplies power to a strobe light with a resistance of 2200 ohms. How much current is flowing through the strobe light?

Solution:I = I = I = 0.05 A

5. A CD Player with a resistance of 40 ohms has a current of 0.1 amps flowing through it. How many volts supplies the CD player?

Solution:

V = I x RV = 0.1 V x 40 V = 4 V

Quiz:

1) A incandescent bulb allows 1.14 x A of current to pass through when connected to a 220 V source. What is the resistance of the bulb?

2) What amount of current flows through a 90.0 wire when it is connected to a 120 V source?

3) How much current is drawn by a lamp that has a resistance of 100 when a voltage of 50 V is put across it?

Assignment:

study in advance the electric power.