This is been explained using one more example to have deep understanding of the concepts
Assume you have a tap and tap has a gate valve, if tap is closed no water will flow and if you open the tap a little, little bit of water comes out, assuming if there is no gravity in the earth, even after you open the tap the water will never come out because gravity is the end device or load which draws the water or current. Like wise only if you attach the load or end device to the battery (source) current flow will occur
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