![]() One slide may be steeper than the other (so water flows down more easily, it has less resistance) but they start at the same height on the cliff. Think of the wires as a water slide down the cliff. Think of voltage as the height of a cliff. Things that are in parallel have the same voltage. This is one of the most fundamentally important concepts in Electrical Engineering, and there are a few things to be learned from this:ġ. If you switched those two resistors absolutely nothing would be different. As beginning engineers, current sources are not familiar because they are buried inside integrated circuits.Ĭurrent wants to "get away" from resistance, so the lower your resistance, the more current will pass through. Most transistors (MOSFET, Bipolar) and the old vacuum tubes have a region of operation where they act just like a current source. If you change the resistor to 1000 ohms, the current will still be 1 mA and the voltage generated by the current source will rise to V = 1 mA x 1000 ohms = 1 V. If you connect a 100 ohm resistor across the current source, the voltage will be V = 1 mA x 100 ohms = 0.1 V. Example: suppose you have a constant current source set to current = 1 mA. Depending on what it is connected to, a current source provides whatever voltage is needed to keep the current on its terminals constant. When you put a current source in a circuit, the current through the source is always a constant value. A constant current source is designed to generate a controlled current. ![]() If you change the resistor to 10 ohms, the voltage will still be 1.5 V but the voltage source will now generate a current of 1.5/10 = 150 mA.Ĭurrent sources may seem a little strange, but they behave exactly like a voltage source, but with current being controlled. Example: a 1.5 V battery connected to a 100 ohm resistor will generate a current of 1.5/100 = 15 mA. Depending on what it is connected to, a voltage source provides (generates) whatever current is needed to keep the voltage on its terminals constant. ![]() When you put a constant voltage source in a circuit, the voltage across its terminals is always a constant value. The difference between them lies in which parameter (voltage or current) is being controlled.Ī constant voltage source (like a battery) is designed to generate a controlled voltage. The potential difference across the 5 Ω resistor is 10 V (found in part a) and the resistance of this resistor is 5 Ω.Voltage and current sources generate both voltage and current. We find the current through a component by dividing the potential difference across the component by the resistance of the component. The reading on A 1 will be the current through the 5 Ω resistor (as there is only 1 component on this branch). I am going to work out the current for A 1 first. We work out the current for A 1 and A 2 separately. This part asks us to find the values for the current on A 1 and A 2. ![]() Therefore, the reading on both V 1 and V 2 will be 10 V as all of the components in the parallel circuit receive this full potential difference. The diagram of the circuit tells us that the source potential difference from the cell is 10 V. This is a parallel circuit and we know that the potential difference is the same across all components in a parallel circuit all of the components in a parallel circuit receive the full source potential difference from the battery or cell. This part asks us to work out the values for the potential difference on voltmeter 1 and 2. A) The potential difference values on V 1 and V 2
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