Dc Circuits and Ohm’s Law.

DC Circuits and Ohm’s Law.

Answers

1. State the equation for Ohm’s law. What do the variables V, I, and R stand for, and what are the units of each? Of the units listed, which one is equivalent to coulomb/second?

Ohm's Law:R=VI

The variable “V” stands for Voltage, the unit used for voltage is Joules/Coulombs. “R” stands for Resistance and it is measured in units of Ohms. Lastly “I” stands for Currents and its unit is measures as Coulombs/seconds.

2. From Part 2.1.1 (Voltage Source): Produce a graph of output voltage V out as a function of the sliding contact position x, measured from the bottom end of the slide wire resistor. Verify that the data points fall on a straight line rather than a curve (don’t actually compute the slope). Did the current change while you varied the sliding contact positionx?

Power Supply |

| |

Position x (cm) | Voltage V |

0 | 0 |

2 | 0.25 |

4 | 0.45 |

6 | 0.7 |

8 | 0.95 |

10 | 1.2 |

12 | 1.45 |

14 | 1.65 |

16 | 1.85 |

18 | 2.1 |

20 | 2.45 |

3. From part 2.1.2 (Ohm’s law ): Produce a graph of voltage V as a function of current I. Compute the slope, which will give the resistance R ( in ohms) of the resistor. In the lab, you should also have deduced R from the color-coding on the side of the resistor itself ( recall in-lab question 1).Does your value for R fall within the manufacturer's expectations?

Voltage V (V) | Current I (A) |

2.85 | 0.04 |

1.8 | 0.03 |

1.45 | 0.02 |

0.8 | 0.01 |

0.5 | 0 |

The R value obtained from the slope on this graph is 57. This does not fall within the manufacturer’s expectations, which is 47 ±10%.

4. From part 2.1.5 (resistors in series/parallel): Using color code, write the value of each resistor used in this part of the experiment (recall in-lab question 1). From this, compute the total resistance Rtot (i) resistors in series, and (ii) resistors in parallel.

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