Physics Homework

Name Class Section

Report 5 Data and Calculation: Show all your work. (19 points) To get credit, always show your work and explain the number of significant digits you use Data Table I. One resistor: Color Code:

R1= ______330________ Ω + _______________ (1 point)

Measured emf [V]

Measured Voltage

[V]

Measured Current [A]

Calculated Resistance [ ]Ω

Resistance from

color code { ]Ω 1.576 1.549 4.7*e-3

1. Use Ohm’s law: R=V/I to calculate resistance after you measured voltage and current and write it in the table above. (1 point) 2. Determine your % error between the value of the resistor given by color code (consider as standard value) and your calculated value (from point 1).

% error = (1 point)

Is your result consistent with the resistor’s nominal value? Explain. (1 point)

3. Using Eq.1, calculate the internal resistance of your battery.

r = (1 point)

Data Table II. Resistors in series: Record the color code for the 2 resistors used:

Color code orange, orange ,brown gold R1= _________ Ω + __________ (1 point)

Color code green green brown gold R2= ________ Ω + ___________ (1 point)

Measured Voltage [V]

Measured Current [A]

Resistance calculated using Ohm’s Law [ ]Ω

Resistance from color code

[ ]Ω V1=0.575

ITotal =1.7e-3 R1= R1=

V2=0.972 R2= R2=

Vtotal = 1.547 RTotal = Req=

1. Calculate the resistances R1, R2 and Rtotal using Ohm’s Law and the measured currents and voltages. (1 point)

This are your measured value of the resistances to be recorded in the third column of Table II. 2. Calculate the equivalent resistance Req using the series resistance formula Re=R1+R2. and the values of the resistance provided by the color code. This will be your standard value of the total resistance. Record it in the last column of Table II. (1 point)

3. Determine your % error between the two values found for the total resistance.

% error = (1 point)

Is your result consistent with the formula for resistors in series? Explain. (1 point)

Data Table III. Resistors in parallel: Record the color code for the 2 resistors used:

Color code orange, orange, brown, gold R1= Ω +

Color code brown, black, brown, gold R2= Ω +

Measured Voltage [V]

Measured Current [A]

Resistance calculated using Ohm’s Law [ ]Ω

Resistance from color code

[ ]Ω

Vtotal = 1.552 I1= 4.7e-3 R1= R1=

I2=2.8e-3 R2= R2=

ITotal =7.5e-3 RTotal = Req=

1. Calculate the resistances R1, R2 and Rtotal using Ohm’s Law and the measured currents and voltages. (1 point) This are your measured value of the resistances to be recorded in the third column of Table II. 2. Calculate the equivalent resistance Req using the parallel resistance formula Eq. (2) and the values of the resistance provided by the color code. This will be your standard value of the total resistance. Record it in the last column of Table III. (1 point) 3. Determine your % error between the two values found for the total resistance.

% error = (1 point)

Is your result consistent with the formula for resistors in parallel? Explain. (1 point)

Data Table IV. Wheatstone bridge (1 point)

Trial R1 [ ]Ω R2 [ ]Ω R3 [ ]Ω Rx [ ]Ω

1 139

2 49

The rheostat maximum resistance is 280 Ω, are your results in accordance with this value? Yes no (circle one). Explain (keep in mind that for trial 1 the rheostat resistance is about 1/3 of its maximum value; for trial 2, about 2/3). (1 point)

Check your understanding, answer the questions: 1. What can you say about current and voltage in a series circuit. Explain the differences. Draw a circuit with 2 resistors in series and clearly explain.(1 point)

. 2. What can you say about current and voltage in a parallel circuit. Explain the differences. Draw a circuit with 2 resistors in parallel and clearly explain. (1 point)

Measuring resister with 1 meter Rx=r2*r3/r1