• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Ohm's Law Physics Lab #20

Extracts from this document...

Introduction

Ohm’s Law

Physics Lab #20

Name: Diana Abou Hassan

Partners: Sara Jaber

Michael Muhanna

Rami Jachi

Date Performed: 14/11/2002

Date Due: 21/11/2002

Teacher: Mrs. Khoury Saab

Objective:

The objective of this lab is to determine the relationship between the potential difference across a conductor and the electric current through it. \

Materials:

• Low voltage variable DC power supply\
• Two different resistors
• 2 digital multimeters
• connecting wires

Procedure: Please refer to lab sheet.

Data Collected:

## Resistor 2

 Voltage (V) 1 1.5 2 2.5 3 3.5 Current (mA + 0.01mA) 0.42 0.72 1.16 1.56 1.91 2.3 Potential Difference (V + 0.001V) 0.526 0.877 1.404 1.893 2.324 2.796

Middle

2.359

2.793

Resistor 2 = 1.202 KΩ

Resistor 7 = 5.07 KΩ

## Light Bulb

Before lighting up:

 Voltage (V+ 0.0001V) 0.0069 0.0781 0.578 0.656 0.759 Current (mA+ 0.01mA) 0.9 10.5 81.3 92.4 109.7

The light bulb lit up at:

 Voltage (V+ 0.0001V) 1.001 Current (mA+ 0.01mA) 149.3

After lighting up:

 Voltage (V+ 0.0001V) 1.609 1.831 2.116 Current (mA + 0.01mA) 182.3 200 223.5

Data Analysis:

Calculate the slope of each graph:

Sample Calculation:

Slope of Resistor 2 = (y2 – y1) / (x2 – x1)

= (2.30 V – 0.42V )/(2.796mA – 0.526mA)

= (2.30 V – 0.42V )/(0.

Conclusion

Sources of Error:

The manual adjustment of the voltage may have caused some error as we may have not adjusted it to the exact values required. If there were a more detailed and precise knob, it could reduce the error. Also, the wire were very rusty therefore acting as very poor conductors. The obvious solution would be to use newer wires.

Conclusion:

The purpose of this lab was to see how the potential difference and the electric current going through a conductor are related. By graphing the results it showed that they were directly proportional. This proved to be correct also for the cold resistivity of the light bulb, however the resistivity of the light bulb after it lit up contradicted Ohm’s law as the resistivity did not remain constant.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related AS and A Level Electrical & Thermal Physics essays

1.  4 star(s)

Thus, the average current after 20 minutes is 0.95 A �10.5%. Time: Time = 60 seconds x 10 minutes Time = 600 seconds Percent uncertainty of time = Percent uncertainty of time � 0.833% The percent uncertainty for time is approximately 0.833%.

2.  ## Measurement of the resistivity of Nichrome

5 star(s)

(V) An ammeter (0-1A) Record the current (A) Several leads Join components in the circuit 1. Check if there is a zero error of the ammeter and the voltmeter. 2. The apparatus shown in the diagram below was set up. Check whether the ammeter and the voltmeter are linked in the correct range.

1.  ## Investgating resistivity - Planning and Implementing

4 star(s)

the variable resistor, allowing multiple values of the current and voltage through any length of wire to be taken. A variable to be kept constant is the temperature of the wire, to allow these different values of current and voltage to be recorded without changing R.

2. ## Finding the Resistivity of a Wire

However, my graph shows that this was fairly irrelevant, due to the reliability of the line for best fit. o Area of cross-section of wire: I cannot be sure that the wire was cylindrical throughout the wire, which could have affected the resistivity value, though by taking several readings and

1. ## Characteristics of Ohmic and non-Ohmic Conductors.

In this section, I will plan my experiments. I am going to investigate the characteristics of Ohmic and non-ohmic conductors by experiments. For this, I am going to first experiment with a metal, a filament lamp, and a thermistor. The basic Apparatus I will need is: * A cell with a power supply of 1.5v * A voltmeter (0-2 V)

2. ## Characteristics of Ohmic and Non-Ohmic Conductors.

Conductors and semiconductors * CONDUCTORS The electron theory states that all matter is comprised of molecules, which in turn are comprised of atoms, which are made up of protons, neutrons and electrons. The electrons in an atom play the most important role with reference to the conduction of electricity.

1. ## Coulombs Lab Report

The method we used to charge them, friction by means of a cloth and acetate strip, is almost impossible to measure. Throughout each of the five trials nothing was changed as we simply wanted 5 identical trials.

2. ## Physics - Resistivity

Mathematically the temperature dependence of the resistivity '?' of a metal is given by a formula called the Bloch-Gruneissen formula. The Bloch-Gruneissen equation is quite complicated and is as follows. Different materials also affect the resistance of the wire, for example copper is a better conductor than steel, steel is a better conductor than silicon, and so on. • Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to 