Electricity
Light
noun
Electricity energy is just a fancy way to say electricity.
でんき
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
電気をつけてください。
Please turn on the light.
電気をつけっぱなしにしないでって言ったじゃん！かせぎが少ないんだから、ちゃんと電気代せつやくにきょう力してよ。
I told you not to leave lights on. You don't earn very much, so you'd better cooperate to save on the electricity bill!
子供の頃は暗闇を恐れていたが、今は電気料金の請求書を受け取る度に、光が怖いと思うよ。
When I was little I was afraid of the dark. Now, when I get my electric bill I’m afraid of the light.