1:20 PM o Verizon Close Ohm\'s Law Measurements of Current Petential Difference

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1:20 PM o Verizon Close Ohm's Law Measurements of Current Petential Difference and Resistance Cautions The electrical energy available from ordinary electrical outlets and also some laboratory devices are capable of doing serious (even fatal) harm to you. Treat them with healthy respect. The amount of energy which can be produced by flashlight batteries (.Sv)is quite harmless, except they can cause a wire to heat up enough to bum you. Electrical meters can be seriously damaged by overloading them. Always measure an unknown voltage or current by starting on the highest scale available. After you have a rough measurement, you can select a more appropriate (more sensitive) scale if necessary. The accuracy of measurements using an analog meter is greatest when the needle has significant deflection. So you want a large deflection for good results, but choosing atoo sensitive range can destroy the meter. Meters, like batteries have a positive and negative terminals. For Ammeters and Voltmeters the positive side of the meter should go closer to the positive side of the battery than the negative side. If a meter tries to deflect to the left, that indicates the meter is hooked up in reverse. Remove the power, reverse the connections to the meter and try again. If a meter needle is ever pinned all the way to the maximum end of the scale, turn off the power in the circuit immediately. Never connect an ammeter in parallel with a battery! Part I Measure the potential difference between the battery tenminals by connecting one lead from the meter to each end of the battery. Do this for both batteries. Put both batteries together connecting the positive ofone to the negative of the other. This is called a series connection. Measure the voltage of the two batteries together. How is this related to their individual measurements? Part 2 Connect the battery, ammeter, and a 47 ohm resistor in a closed loop series circuit. Connect the voltmeter to measure the potential difference between the ends of the resistor. The ammeter will measure the current leaving the battery. Record both the current and the potential difference indicated. Why do we say the cincuit in the figure below measures the current leaving the battery? Is that necessarily the same as the current through the resistor in the figure? Explain before continuing. The figure below shows pictorially and schematically how to set up the current leaving the battery on the left and right sides respectively. Note: Schematics do not normally indicate the polarity of meters. The positive side of the battery is the longer of the two parallel bars

Explanation / Answer

part1

Each battery voltage is measured to be equal to 1.5V

Two series connection of 1.5V battery gives the total volts of 3 V ( 1.5+1.5)

Part2

The ammeter is a current measuring device that is always connected in series with the circuit so that the same current flows through all the network components which passes through the serially connected ammeter.

The current can be measured using Ammeter and voltage can be measured across the resistor using voltmeter.

Part3

The graph of potential difference versus current flowing through the circuit can be plotted ( 'V' on The Y axis and ' I' on the X axis)

the slope of the above graph gives the resistance value.

usually graph follows a linear characteristics.

Part4

As the current decreases the brightness of the bulb decreases

By increasing the resistance we decrease the current flowing through the circuit and vice versa

the voltage is directly proportional to current and the constant is resistor

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