Electrical Calculations

Ohm’s law describes the relationship between current, resistance, and voltage.

As voltage

increase,

current

increases

As resistance decreases, current

increases

Electric power is the rate at which electrical energy is changed into other

forms of energy

Power is measured in WATTS

Electrical energy is electric power multiplied by time. It is usually expressed in kilowatt-hours.

A KILOWATT is 1000 watts!

Find these at your house! They show the power company how much

electrical energy you use.

Self-Check

Question 1

As resistance goes up, what happens to the current?a. The current goes up.b. The current goes down.c. The current stays the same.d. The current disappears.

Question 1

As resistance goes up, what happens to the current?a. The current goes up.b. The current goes down.c. The current stays the same.d. The current disappears.

Question 2

What is the rate at which electrical energy is changed into other forms of energy?a. electric powerb. voltagec. electrical energyd. amps

Question 2

What is the rate at which electrical energy is changed into other forms of energy?a. electric powerb. voltagec. electrical energyd. amps

Question 3

What is the voltage if the current is 4 A and the resistance is 10 Ω?a. 4 Vb. 40 Rc. 10 Vd. 40 V

Question 3

What is the voltage if the current is 4 A and the resistance is 10 Ω?a. 4 Vb. 40 Rc. 10 Vd. 40 V

Question 4

How much electrical energy does a 75 W light bulb use if it is on for 4 hours?a. 150 kWhb. 150 Wc. 300 kWhd. 300 W

Question 4

How much electrical energy does a 75 W light bulb use if it is on for 4 hours?a. 150 kWhb. 150 Wc. 300 kWhd. 300 W

Question 5

In the formula P = V X I, what does the I stand for?a. currentb. intensityc. voltaged. resistance