Power & Work Done

First of all, Power is the rate of energy being transferred, the equation for this is P=E/T or (Power = Energy / Time).

Work donee works at what rate "Work" is done, so if you push a car down a ramp it is considered to be work done, the equation for this is P=W/T or (Power = Work Done / Time). 

But both these follow the same measurements, power is in watts, energy in joules, and time in seconds. 

So let's use both equations to figure out which lamp is better.
Lamp 1 transfers 1200 joules over 20 seconds.
Lamp 2 transfers 1500 joules over 30 seconds.

For this equation, we will use the first equation, or the P=E/T. Now, we plug in lamp 1's numbers, so 1200J / 20s = 60 watts.
For the 2nd lamp, we put 1500J / 30s = 50 watts.
So even though the second one has more power in the form of joules, because of its time in seconds, the amount of power (watts) is worse than the 1st. 

Let's figure out how much power an 1100-watt microwave need, so first let's turn it on for 3 minutes. First lets change out 3 minutes into 180 seconds by multiplying the 3 * 60(minutes), now we can do 1100 * 180 =  198,000 joules. But when we get a big number we can convert it to kilojoules or 198,000 / 1000 = 198KJ.