Fizyka - program rozszerzony I
Review the components of a circuit and their symbols such as battery, resistor, and switch. Analyze how the power of a resistor is related to the current and electric potential difference across the resistor.
|Szybkość, z jaką energia wydziela się na oporniku, jest równa iloczynowi spadku potencjału elektrycnego na oporniku i natężenia prądu płynącego przez opornik. Wielkość skalarna, której jednostką jest wat (|
Definicje i symbole elementów obwodu
Resistors are electrical components that resist current and expends voltage within a circuit.
Baterie to elementy dostarczające energię elektryczną.
Baterie mają bieguny dodatnie u ujemne. Ujemny biegun jest oznaczany krótką linią, a dodatni długą.
Switches turn the flow of current through a circuit pathway on and off. When the switch is open, no current flows because there is a gap in the circuit (Figure 3).
When the switch is closed, current can flow because the circuit is continuous (Figure 4).
A node (or junction) is a place where two or more circuit elements join together. Figure 5 below shows a single node (the black dot) formed by the junction of five electrical components (abstractly represented by orange rectangles).
DC circuit types
A simple circuit contains the minimum amount of components that allow it to be a functional electric circuit: a voltage source
(battery), a resistor , and a loop of wires for current to flow around (see Figure 6 below). We usually ignore any resistance from the wires.
In a simple circuit, the voltage supplied by the battery
is the voltage expended by the resistor , and there is only one current in the circuit.
A closed circuit has a continuous pathway for current to flow through. In other words, there are no gaps in the circuit.
An open circuit has a gap in the circuit that does not allow current to flow through. The gap can be caused by an open switch, a broken component, or broken wire.
A short is a pathway of zero resistance within a circuit (see the blue wire in Figure 9). When there is a short circuit, all the current flows across the short because the current prefers the path of least resistance.
Figure 10 below shows how closing a switch
can divert all the current from resistor . When switch is open (see Figure 10A), the current flows out of the positive terminal of the battery towards node . Since the switch is open, no current flows through the switch and all the current flows through resistor . When the switch is closed (see Figure 10B), it forms a short around resistor . Now, once the current reaches , the current bypasses and flows through the switch.