Paradoxically enough, water or hydraulics to be specific and electricity react to barriers and loads in much the same way. A garden hose presents resistance to flow even with no kinks. Lay it out in a straight line and with nothing attached water will freely flow out the other end. Or does it? The hose itself much like wire causes a resistance to the flow, however minute it may be. If you rolled the hose up and turn on the water again the coiled hose will create even greater resistance. If this was an electronic circuit that coil of wire could be called a choke because it causes a choking affect in AC circuitry like analog radios or a Crossover in a speaker.
Now the hose gets a cut or breaks and you opt to repair it. The coupling that you use will cause additional resistance to the flow. For arguments sake we'll say your coupling was for a smaller hose. That coupling becomes an orifice restricting the flow even greater creating a significant pressure drop across the coupling than it would if you had a larger one. In fact a pressure gauge used for measuring this will be connected to both sides of the coupling with two connectors and the indicated pressure Will be the difference in potential (pressure drop or 'Delta P'). In electronics that coupling is a resistor and your DMM (digital multi meter) is your pressure gauge. By placing a test lead On both sides of the component you will read the Delta V, or voltage drop as it is referred to.
I hope this helps. Now a word from the safety team. Household current is very dangerous. You may hear electricians talk about getting bit and not really emphasizing the gravity of what COULD HAPPEN. Electricity flowing through your body creates a wound path for lack of a better explenation from the point of entry to exit burning tissue and breaking bones. I highly recommend skills training to at least recognize what hazardous voltage circuits look like. IE your microwave oven plugs into 120vAC bit the voltage that does the cooking is stepped up to 10kv or 10,000 volts. Most test ewuipment will be rated for use up to 600 volts. If you put your DMM on 10kv it will straighten your legs so fast it will launch you across the room. Th sudden stop can cause spinal injury or worse. I have personally witnessed it and yes, he was smoking.