2.5 Electrical energy and Power

Front

What is electrical power?

Back

Electrical power is the rate at which electrical energy is transferred by an electric circuit, measured in watts (W).

Front

What is the formula for calculating electrical power?

Back

P = VI, where P is power in watts, V is voltage in volts, and I is current in amperes.

Front

What is the relationship between voltage, current, and resistance?

Back

Ohm's Law states that V = IR, where V is voltage, I is current, and R is resistance.

Front

How do you calculate electrical energy consumed?

Back

Electrical energy (E) can be calculated using the formula E = Pt, where P is power in watts and t is time in seconds.

Front

What does it mean if an appliance is rated at 80 W?

Back

It means the appliance consumes energy at a rate of 80 joules per second.

Front

How do you convert time from minutes to seconds?

Back

Multiply the number of minutes by 60 to convert to seconds.

Front

What is the unit of electrical energy?

Back

The unit of electrical energy is the joule (J).

Front

How do you calculate the current flowing through a resistor?

Back

Use Ohm's Law: I = V/R, where I is current, V is voltage, and R is resistance.

Front

If a current of 0.5 A flows through a resistance of 10 ohms, what is the voltage?

Back

Using Ohm's Law: V = IR = 0.5 A * 10 ohms = 5 V.

Front

What is the total energy consumed by a device rated at 80 W over 2 hours?

Back

E = Pt = 80 W * (2 hours * 3600 seconds/hour) = 576000 J or 576 kJ.