Resistors in Series and Parallel Circuits Experiment - GCSE Physics Required Practical

Summary

This educational video demonstrates how to measure the resistance of resistors in series and parallel circuits. The experiment uses identical resistors, two cells for power, an ammeter, and a voltmeter. It begins by testing a single resistor, recording current and voltage to calculate resistance. Then, it compares resistance when resistors are connected in series and parallel, showing how total resistance changes with different configurations.

Takeaways

• 🔬 The experiment aims to measure the resistance of resistors in series and parallel circuits.
• 🔌 Identical resistors are used, with their values concealed for discovery during the experiment.
• 🔋 A simple circuit is set up using two cells with a maximum voltage of four volts.
• 📏 An ammeter is used to check the current flow and ensure the circuit components are functioning.
• 🔌 The first resistor is connected, and the ammeter reads a current of 0.26 or 0.27 amps.
• 🔌 A voltmeter is connected in parallel to the resistor to measure the voltage, which reads 2.68 volts.
• 🧮 With current and voltage known, the resistance of the first resistor is calculated using Ohm's Law (V=IR).
• 🔄 The process is repeated with the second identical resistor to verify consistency.
• 🔗 When resistors are connected in series, the total resistance increases, as measured by the ammeter and voltmeter.
• 🔄 In parallel, the resistors combine to decrease the total resistance, resulting in a higher current and lower voltage across each resistor.
• 📊 The experiment concludes with measurements for current and voltage in both series and parallel configurations, allowing for the calculation of total resistance in each case.

Q & A

What is the purpose of the experiment described in the transcript?

The purpose of the experiment is to measure the resistance of resistors both in series and in parallel configurations.

What is the maximum voltage the circuit can handle according to the transcript?

The maximum voltage the circuit can handle is four volts.

How many cells are used in the circuit to achieve the maximum voltage?

Two cells are used in the circuit to achieve the maximum voltage of four volts.

What instruments are used in the experiment to measure current and voltage?

An ammeter is used to measure current, and a voltmeter is used to measure voltage.

What is the initial current reading when one resistor is connected to the circuit?

The initial current reading is 0.26 or 0.27 amps when one resistor is connected to the circuit.

What is the voltage reading when the voltmeter is connected in parallel to the resistor?

The voltage reading is 2.68 volts when the voltmeter is connected in parallel to the resistor.

How does the resistance of a resistor get calculated in the experiment?

The resistance of a resistor is calculated using Ohm's Law, which is Voltage = Current × Resistance.

What happens to the current when two identical resistors are connected in series?

The current decreases when two identical resistors are connected in series due to the increased total resistance.

What is the expected change in current when resistors are connected in parallel?

The current is expected to increase when resistors are connected in parallel because the total resistance decreases.

How does the experimenter ensure that the wires are connected correctly when changing from series to parallel?

The experimenter ensures that the wires are connected correctly by carefully observing the connections and removing the voltmeter before making changes.

What is the final current reading when the resistors are connected in parallel?

The final current reading is between 0.47 and 0.48 amps when the resistors are connected in parallel.

Outlines

00:00

🔬 Measuring Resistance in Series and Parallel Circuits

This video script describes an experiment to measure the resistance of resistors in both series and parallel configurations. The experimenter uses identical resistors with obscured values and connects them to a simple circuit powered by two cells, not exceeding four volts. An ammeter and voltmeter are used to measure current and voltage. Initially, a single resistor is tested, yielding a current of 0.26 to 0.27 amps and a voltage of 2.68 volts, allowing the calculation of its resistance. The experimenter then replaces the first resistor with another identical one, observing similar readings. Subsequently, the resistors are connected in series and parallel to observe changes in current and voltage, which are used to calculate the total resistance in each configuration. The experiment concludes with the observation of higher current due to the parallel connection and the corresponding voltage and current readings for resistance calculation.

Keywords

💡Resistance

Resistance is a property of materials that opposes the flow of electric current. In the context of the video, resistance is a key concept as the experiment aims to measure it. The script describes measuring the resistance of individual resistors and how it changes when resistors are connected in series or parallel. For example, when a single resistor is connected to a circuit, the voltmeter reads 2.68 volts, and the ammeter reads 0.26 or 0.27 amps, which allows the calculation of the resistor's resistance using Ohm's Law (Resistance = Voltage/Current).

💡Series

In the video, 'series' refers to a circuit configuration where components are connected end-to-end in a single path so that the current flows through each component in turn. The script mentions connecting two identical resistors in series and observing the effect on the total resistance and current. This is a fundamental concept in electronics, as the total resistance in a series circuit is the sum of the individual resistances.

💡Parallel

Parallel, as used in the script, describes a circuit configuration where components are connected in multiple paths so that the voltage across each component is the same, but the current is divided. The experiment connects resistors in parallel and measures the resulting current and voltage, demonstrating that the total resistance in a parallel circuit is less than the smallest individual resistance.

💡Resistors

Resistors are electronic components designed to oppose the flow of electric current. The script involves using resistors in an experiment to understand their behavior in different circuit configurations. The experimenter covers the value of the resistors to introduce an element of discovery, emphasizing the learning objective of determining resistance through measurement.

💡Circuit

A circuit, as mentioned in the script, is a closed loop through which electric current flows. The video describes setting up a simple circuit with cells (batteries), an ammeter, and a voltmeter to measure current and voltage across resistors. The circuit is fundamental to the experiment, as it allows for the practical application of electrical principles.

💡Ammeter

An ammeter is an instrument used to measure the electric current in a circuit. In the script, the ammeter is used to check that the circuit is functioning correctly by measuring the current flowing through a resistor. It's a crucial tool in the experiment, providing data necessary for calculating resistance.

💡Voltmeter

A voltmeter is an instrument used to measure the electric potential difference (voltage) between two points in a circuit. The script describes using a voltmeter to measure the voltage across a resistor, which, combined with the current measurement from the ammeter, allows for the calculation of resistance.

💡Cells (Batteries)

Cells, or batteries, are energy sources that provide the voltage necessary to drive current through a circuit. The script mentions using two cells to create a maximum of four volts for the experiment. The cells are essential to the circuit as they provide the power needed to observe the behavior of the resistors.

💡Ohm's Law

Ohm's Law is a fundamental principle in electrical engineering that states the relationship between voltage (V), current (I), and resistance (R) in a circuit: V = IR. The script alludes to this law when calculating resistance using the measured voltage and current from the circuit with a single resistor.

💡Current

Current is the flow of electric charge in a circuit, measured in amperes (amps). The script describes measuring current using an ammeter when a resistor is connected to the circuit. Current is a key variable in the experiment, as it is used in conjunction with voltage to calculate resistance.

💡Voltage

Voltage, also known as electric potential difference, is the force that pushes electric charge through a circuit and is measured in volts. In the script, voltage is measured using a voltmeter across a resistor to determine the resistance. Voltage is a critical factor in the experiment as it is one of the variables used to calculate resistance.

Highlights

Experiment aims to measure resistance of resistors in series and parallel.

Use of identical resistors with values concealed for discovery during the experiment.

Simple circuit setup with two cells capped at a maximum of four volts.

Utilization of an ammeter to verify the circuit's functionality and measure current.

First resistor tested shows a current of 0.26 or 0.27 amps, indicating a working circuit.

Voltmeter reading of 2.68 volts obtained with the first resistor.

Calculation of the first resistor's resistance using Ohm's Law (V=IR).

Second resistor of identical value tested for consistency.

Fluctuating readings between 2.4 and 2.5 volts for the second resistor.

Introduction of resistors in series to observe combined resistance.

Ammeter reading changes when resistors are connected in series.

Voltmeter reading taken in parallel to measure total voltage across series-connected resistors.

Transition to testing resistors in parallel to observe changes in current and voltage.

Higher current observed when resistors are connected in parallel.

Final voltmeter reading of 2.46 volts and ammeter reading of 0.47 or 0.48 amps with resistors in parallel.

Analysis of total combined resistance for resistors in parallel.

Transcripts

so in this experiment we're going to be

measuring the resistance

of resistors both in series and also

parallel so i've got a couple of

resistors here these ones are identical

and i've just covered up the value of

these resistances so we can actually

work that out in the experiment

now the first thing we're going to do is

we're going to connect it into a very

simple circuit

i've got my cells here i'm actually

going to be using just

two of them because we're going to go up

to a maximum

and it says on here a maximum of four

volts so i'm just going to use

two of these um and we've got an ammeter

and a voltmeter

so the first thing i'm going to do is

just connect one of these resistors

um into the circuit and i'm going to put

it just

with the ammeter and this allows me to

check that the ammeter is working

that all of the wires are working and

that this resistor is working

as well so we can see when i do that

that we've got a value of 0.26 or

27 amps okay so we know that the circuit

is working so far

and what i'm then going to do is i'm

going to connect my voltmeter

in parallel to the resistor

and this gives a reading of 2.68

volts okay so we've got the current

we've got the potential difference of

the voltage

and that means we can now calculate the

resistance

of this resistor so if you want to take

a record of these readings now

i'm then going to take this resistor out

and i'm going to replace it with the

other resistor

now this is the same value so these

readings should be similar

and we can see that this one is

fluctuating between 2 4 and 2 5. so

it's really your judgment about which

value you use so

we've now worked out the resistance of

these two individual resistors we're now

going to see what happens when we

connect them

in series so to do that

just to make sure that i don't get

confused with the wires

if i just take the voltmeter out what

i'm now going to do

is just put the two resistors like this

i'm going to connect them up with this

wire and once again

now they're in series we can see there's

a reading on the ammeter

and if i put the voltmeter in parallel

this is the reading that we're going to

take

so what you can now do is you can look

at the total resistance of this

combination of resistors

in series now the last thing we're going

to be doing is looking at resistors

in parallel so again once again i'm

going to take the voltmeter out

i'm just going to disconnect the

resistors

and now i'm going to connect them up in

parallel

so it's just worth taking care keeping

an eye of where

all of the wires go so we can see now we

have a higher current

because we've got these in parallel and

i'm just going to put

this across the terminals here

okay so now we've got

2.46 volts and that's going to be across

both

of these and we've got a current of 0.47

or four eight

so we've now got readings for the

current

and the voltage and we can now look at

the total combined resistance

of this combination of resistors in

parallel

you