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11.7 Electrical Resistance. Electrical Resistance (R) is a property of matter that describes how difficult it is for electric current to travel through a circuit. SI units: ⤍ Ohm ( Ω )
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11.7 Electrical Resistance Electrical Resistance (R) is a property of matter that describes how difficult it is for electric current to travel through a circuit. SI units: ⤍Ohm (Ω) Ohm’s Law states that the voltage (V) in a conductor is directly proportional to the current (I), if the temperature remains constant.V α I As the voltage applied to a resistor increases, the current through the resistor also increases. SP #1 p.524
11.7 Electrical Resistance Insulators, such as plastic and rubber, have a high resistance; they do not allow electrical currents through easily. Conductors, such as metals, have a low resistance; they allow electrical currents through more easily. Resistors are electrical devices that have a specific resistance. For example, speaker wires would use a resistor with a low resistance to allow a large current to reach the speaker to produce loud sounds. If you want a low current in a circuit so that fine wires are not damaged, it makes sense to use a resistor with a high resistance.
11.7 Homework • Practice # 1, 2 p.525 • Questions # 1, 2, 5, 6, 9 p.526
11.8 Resistors in Circuits Equivalent Resistance is the total resistance of a group of resistors in a circuit. You can use a combination of Kirchhoff’s Laws and Ohm’s Law to derive the equations for equivalent resistance for resistors in both series and parallel circuits.
11.8 Resistors in Circuits SP #1 p.527
11.8 Resistors in Parallel SP #1 p.528 SP #1 p.529
11.8 Homework • Practice # 1, 2 p.529 • Practice # 1 p.530 • Questions # 5 p.530