Physics 7 Lesson 27: Practice: Measure amperage and voltage for a series circuit
1. Summary of theory Tóm
1.1. Experiment target
- Knowledge: Know how to connect 2 light bulbs in series.
- Skills: Practice measuring and detecting the rules of electricity and electricity in the circuit connected in series with 2 bulbs.
- attitude: Good sense in practice period.
1.2. Laboratory instruments
- 3V . Power Supply
- Two identical flashlight bulbs.
- 1 milli ammeter has a current of 0.5A and a current of 0.001 A
- 1 Voltmeter with current: 6V and DC: 0.1V
- 1 switch, lead
- Sample report of groups
- Side table to answer the prep questions.
1.3. Theoretical basis
- Xfirst, X2 … SHOCKINGn are electrical devices
- Ifirst, I2 … In fewAB is the amperage through the electrical equipment and in the main circuit.
- UAB is the voltage at the two ends of the circuit.
- Ufirst, U2 ... Un is the potential difference between the two ends of each electrical device, respectively.
– A series-connected circuit is a circuit consisting of electrical devices connected together in a consecutive array.
- Figure 1.1 shows electrical devices Xfirst, X2…Xn connected in series.
a) Amperage in the circuit connected in series
– In a series-connected circuit, the amperage through the electrical devices in the circuit is the same.
- We have: IAB = Ifirst = I2 = … = In
– Measure the amperage through the main circuit or electrical devices, we just need to use an ammeter connected in series to that circuit.
a) The potential difference between the two ends of the circuit connected in series
– In a series-connected circuit, the potential difference between the two ends of a circuit consisting of electrical devices connected in series is equal to the sum of the potential differences between the two ends of each component device.
- We have: UAB = Ufirst + U2 + …+ Un
– To measure the potential difference between the two ends of any electrical device, we use a voltmeter connected in parallel with that electrical device in the circuit.
2. Practice report
* Fill the right words in the blank
a. Measure the amperage in ammeter
The unit of amperage is . amps, denoted by A.
Infected serial ammeter to the circuit so that the pin (+) of the ammeter is connected to the terminal positive of the power supply.
b. Measure the voltage in voltmeter.
The unit of voltage is . Voltage, denoted by DRAW.
Connect two pins of the voltmeter direct on two points of the circuit to measure the potential difference between those two points, so that its (+) pin is connected towards the terminal positive of the power supply.
* Measure the strength of the current for a series circuit
a) Draw a diagram for the circuit shown in Figure 27.1a in the box below:
b) Measurement results:
In a series circuit, the currents are of equal magnitude at different locations of the circuit: Ifirst = I2 = I3
* Measure potential difference for series circuit
a) Draw a circuit diagram similar to figure 27.2 in the frame below, in which a voltmeter is connected to measure the potential difference between the two ends of the lamp D.2.
b) Measurement results:
For a circuit consisting of two strings connected in series, the potential difference between the two ends of the circuit is equal to the sum of the voltages across each lamp: U13 = Utwelfth + U23
Question 1: Give the circuit as shown. Know on the RED bulbsfirst, D2, D3 write 1V, 2V, 3V respectively. The reading of the ammeter is I = 0.5A. Find the potential difference between the two terminals of the source and the current Ifirst, I2, I3 through three RED lightsfirst, D2, D3.
Verse 2: Given a circuit consisting of two lights connected in series to a 12V power source, know the amperage passing through the RED lampfirst is 0.25A.
a) Calculate the current through the RED lamp2.
b) If the voltage across lamp 2 is 4.5V, what is the voltage across lamp 1?
Question 3: Given an active measuring instrument as shown in the figure. Read the index of the needle at that time.
Verse 4: Given the circuit as shown:
a) RED lightfirst and D2 the same, know the voltmeter Vfirst only 15V, determine the reading of the voltmeter V2 and voltmeter V.
b) With the same circuit as above, replace the voltmeter with ammeter A, Afirst, A2. Know that ammeter A shows 10A. So how many amps are the remaining 2 ammeters reading?
Through the Practice Exercise Measuring amperage and voltage for this series circuit, you need to complete some of the goals given by the lesson such as:
State the relationship between the currents in series and parallel circuits.
State the relationship between voltages in series and parallel circuits.
Connect two bulbs in series and parallel and draw the corresponding diagram.