physics lab report 1

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Page 1 of 12 Phys 202 7:30 – 10:30 Th Name: Genelle N. Estremos Date performed: November 24, 2011 Course and Year: BSChE – 2 Date submitted: November 30, 2011 Group number: 4 Instructor: Ohm’s Law I. Objectives: To verify Ohm’s Law for a.) Constant Voltage b.) Constant Current c.) Constant Resistance II. Apparatus: Resistance Board, (Voltmeter, Ammeter) or Multi-tester, Dry Cell, Connectors III. Figures of Experimental Setup Standard Value of Resistance Part 1: Constant Voltage Part 2: Constant Current A B C D E F Multitester (Ohmeter A B C D E F V - + CELL + - A + - A B C D E F V - + CELL + - A + -

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Page 1: Physics Lab Report 1

Page 1 of 12

Phys 202 7:30 – 10:30 Th

Name: Genelle N. Estremos Date performed: November 24, 2011 Course and Year: BSChE – 2 Date submitted: November 30, 2011 Group number: 4 Instructor:

Ohm’s Law I. Objectives: To verify Ohm’s Law for a.) Constant Voltage b.) Constant Current c.) Constant Resistance II. Apparatus: Resistance Board, (Voltmeter, Ammeter) or Multi-tester, Dry Cell,

Connectors III. Figures of Experimental Setup

Standard Value of Resistance

Part 1: Constant Voltage

Part 2: Constant Current

A B C D E F

Multitester (Ohmeter

A B C D E F

V - +

CELL + -

A

+-

A B C D E F

V - +

CELL + -

A

+-

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Part 3: Constant Resistance

IV. Data and Results Part 1: Constant Voltage

V (volts) R (Ohms) Io (Amps) Ic (Amps) % Difference 1.45 V 17 Ω 0.080 0.085 5.88% 1.50 V 30 Ω 0.043 0.050 14.00% 1.50 V 50 Ω 0.030 0.030 0.00% 1.50 V 65 Ω 0.020 0.020 0.00% 1.50 V 80 Ω 0.0190 0.019 0.00%

Part 2: Constant Current I (Amps) R (Ohms) Vo (Volts) Vc (Volts) % Difference 0.019 A 17 Ω 0.30 V 0.32 V 0.06% 0.019 A 30 Ω 0.60 V 0.57 V 0.05% 0.019 A 50 Ω 0.90 V 0.95 V 0.05% 0.019 A 65 Ω 1.25 V 1.24 V 0.00 % 0.019 A 80 Ω 1.55 V 1.52 V 0.02%

Part 3: Constant Resistance R (Ohms) I (Amps) Vo (Volts) Vc (Volts) % Difference 18.13 Ω 0.08 A 1.45 V 1.44 V 0.60% 18.60 Ω 0.043 A 0.80 V 0.77 V 3.75% 16.67 Ω 0.03 A 0.50 V 0.54 V 7.41% 20.00 Ω 0.02 A 0.40 V 0.36 V 10.00% 16.67 Ω 0.018 A 0.30 V 0.32 V 6.20%

V. Computations To find the magnitude of volt per line ( ) of the tester that has been used

during the entire experiment, 푉푙푖푛푒 =

푅푎푛푔푒푉푎푙푢푒푛푢푚푏푒푟표푓푙푖푛푒푠

=2.5푉

50푙푖푛푒푠

= 0.05푉푙푖푛푒

A B C D E F

V - +

CELL + -

A

+-

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To find the magnitude of ampere per line ( ) of the tester that has been used during the entire experiment,

퐴푙푖푛푒 =

0.25퐴50푙푖푛푒푠

= 0.005퐴푙푖푛푒

Part 1: Constant Voltage (The constant voltage was generated from a 1.5 V battery.) From point A to point B To find the observed Current (Io),

퐼 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 16푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟖ푨 To find the computed Current (Ic),

퐼 =푉푅

=1.45푉17Ω

= ퟎ.ퟎퟖퟓ푨 To compute the percentage difference between the observed and computed values of the resistance,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.085퐴 − 0.08퐴

0.085퐴 × 100% = ퟓ.ퟖퟖ%

From point A to point C To find the observed Current (Io),

퐼 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 8.5푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟒퟑ푨 To find the computed Current (Ic),

퐼 =푉푅

=1.50푉30Ω

= ퟎ.ퟎퟓퟎ푨 To compute the percentage difference between the observed and computed values of the resistance,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.050퐴 − 0.043퐴

0.050퐴 × 100%

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= ퟏퟒ.ퟎퟎ% From point A to point D To find the observed Current (Io),

퐼 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 6푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟑퟎ푨 To find the computed Current (Ic),

퐼 =푉푅

=1.50푉50Ω

= ퟎ.ퟎퟑퟎ푨 To compute the percentage difference between the observed and computed values of the resistance,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.030퐴 − 0.030퐴

0.030퐴 × 100% = ퟎ.ퟎퟎ%

From point A to point E To find the observed Current (Io),

퐼 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 4.5푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟐퟎ푨 To find the computed Current (Ic),

퐼 =푉푅

=1.50푉65Ω

= ퟎ.ퟎퟐퟎ푨 To compute the percentage difference between the observed and computed values of the resistance,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.020퐴 − 0.020퐴

0.020퐴 × 100% = ퟎ.ퟎퟎ%

From point A to point F To find the observed Current (Io),

퐼 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

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= 3.8푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟏퟗ푨 To find the computed Current (Ic),

퐼 =푉푅

=1.50푉80Ω

= ퟎ.ퟎퟏퟗ푨 To compute the percentage difference between the observed and computed values of the resistance,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.019퐴 − 0.19퐴

0.019퐴 × 100% = ퟎ.ퟎퟎ%

Part 2: Constant Current To calculate the magnitude of resistance (I) used throughout the process,

퐼 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 3.8푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟏퟗ푨 From point A to point B To find the observed Voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 6푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟎ.ퟎퟑퟎ푽 To find the computed Voltage (Vc),

푉 = 퐼푅 = (0.019퐴)(17Ω) = ퟎ.ퟑퟐ푽

To compute the percentage difference between the observed and computed values of the Voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.32푉 − 0.30푉

0.32푉 × 100% = ퟎ.ퟎퟔ%

From point A to point C To find the observed Voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

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= 12푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟎ.ퟔퟎ푽 To find the computed Voltage (Vc),

푉 = 퐼푅 = (0.019퐴)(30Ω) = ퟎ.ퟓퟕ푽

To compute the percentage difference between the observed and computed values of the Voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.60푉 − 0.57푉

0.60푉 × 100% = ퟎ.ퟎퟓ%

From point A to point D To find the observed Voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 18푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟎ.ퟗퟎ푽 To find the computed Voltage (Vc),

푉 = 퐼푅 = (0.019퐴)(50Ω) = ퟎ.ퟗퟓ푽

To compute the percentage difference between the observed and computed values of the Voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.95푉 − 0.90푉

0.95푉 × 100% = ퟎ.ퟎퟓ%

From point A to point E To find the observed Voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 25푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟏ.ퟐퟓ푽 To find the computed Voltage (Vc),

푉 = 퐼푅 = (0.019퐴)(65Ω) = ퟏ.ퟐퟒ푽

To compute the percentage difference between the observed and computed values of theVoltage,

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% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=1.25푉 − 1.24푉

1.25푉 × 100% = ퟎ.ퟎퟎퟖ%

From point A to point F To find the observed Voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 31푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟏ.ퟓퟓ푽 To find the computed Voltage (Vc),

푉 = 퐼푅 = (0.019퐴)(80Ω) = ퟏ.ퟓퟐ푽

To compute the percentage difference between the observed and computed values of the Voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=1.55푉 − 1.52푉

1.55푉 × 100% = ퟎ.ퟎퟐ%

Part 3: Constant Resistance (The average of the resistance was found to be 18.014 Ω) From point A to point F To calculate the current (A),

퐴 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 16.5푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟖ푨 To calculate the observed voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 29푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟏ.ퟒퟓ푽 To compute the resistance (R),

푅 =푉퐼

=1.45푉0.08퐴

= ퟏퟖ.ퟏퟑΩ To find the computed voltage (Vc),

푉 = 퐼푅 = (0.08퐴)(18.01Ω)

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= ퟏ.ퟒퟒ푽 To compute the percentage difference between the observed and computed values of the voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=1.45푉 − 1.44푉

1.45푉 × 100% = ퟎ.ퟔퟎ%

From point A to point E To calculate the current (A),

퐴 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 8.5푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟒퟑ푨 To calculate the observed voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 16푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟎ.ퟖ푽 To compute the resistance (R),

푅 =푉퐼

=0.80푉

0.043퐴 = ퟏퟖ.ퟔퟎΩ

To find the computed voltage (Vc), 푉 = 퐼푅

= (0.043퐴)(18.01Ω) = ퟎ.ퟕퟕ푽

To compute the percentage difference between the observed and computed values of the voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.80푉 − 0.77푉

0.80푉 × 100% = ퟑ.ퟕퟓ%

From point A to point D To calculate the current (A),

퐴 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 6푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟑ푨

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To calculate the observed voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 10푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟎ.ퟓ푽 To compute the resistance (R),

푅 =푉퐼

=0.50푉0.03퐴

= ퟏퟔ.ퟔퟕΩ To find the computed voltage (Vc),

푉 = 퐼푅 = (0.03퐴)(18.01Ω) = ퟎ.ퟕퟕ푽

To compute the percentage difference between the observed and computed values of the voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.54푉 − 0.50푉

0.54푉 × 100% = ퟕ.ퟒퟏ%

From point A to point C To calculate the current (A),

퐴 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 4.5푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟐ푨 To calculate the observed voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 8푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟎ.ퟒퟎ푽 To compute the resistance (R),

푅 =푉퐼

=0.40푉0.02퐴

= ퟐퟎ.ퟎퟎΩ To find the computed voltage (Vc),

푉 = 퐼푅 = (0.02퐴)(18.01Ω) = ퟎ.ퟑퟔ푽

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To compute the percentage difference between the observed and computed values of the voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.40푉 − 0.36푉

0.40푉 × 100% = ퟏퟎ.ퟎퟎ%

From point A to point B To calculate the current (A),

퐴 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×퐴푙푖푛푒

= 3.5푙푖푛푒푠 × 0.005퐴푙푖푛푒

= ퟎ.ퟎퟏퟖ푨 To calculate the observed voltage (Vo),

푉 = 푛푢푚푏푒푟표푓푙푖푛푒푠 ×푉푙푖푛푒

= 6푙푖푛푒푠 × 0.05푉푙푖푛푒

= ퟎ.ퟑퟎ푽 To compute the resistance (R),

푅 =푉퐼

=0.30푉

0.018퐴 = ퟏퟔ.ퟔퟕΩ

To find the computed voltage (Vc), 푉 = 퐼푅

= (0.018퐴)(18.01Ω) = ퟎ.ퟑퟐ푽

To compute the percentage difference between the observed and computed values of the voltage,

% =퐵푖푔푔푒푟푉푎푙푢푒 − 푆푚푎푙푙푒푟푉푎푙푢푒

퐵푖푔푔푒푟푉푎푙푢푒 × 100%

=0.32푉 − 0.30푉

0.32푉 × 100% = ퟔ.ퟐퟎ%

VI. Graphs (Note: x and y axes are not proportional to each other on the following graphs)

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VII. Data Analysis 1. A cell of emf 3.0 volts and internal resistance of 0.01 ohm is connected through an

ammeter of 0.05-ohm internal resistance to a 5.0 Ω rheostat by wire having a total resistance of 0.85-ohm. In the calculation of the current, what percentage error would be made by neglecting all resistances except that of the rheostat?

2. A dry cell when short-circuited will furnish about 30 amperes for a brief time. If its emf is 1.5 volts, what is its internal resistance? An ordinary household electric lamp takes about 1 amp, will it be safe to connect it directly to the dry cell?

푥 + 4푥 − 3푥 + 5

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