Download Lab- Series Circuits

Name: ________________ Partner: _____________________ Date: _____________________
SNC 1D
Investigating Series Circuits
Introduction
For a circuit to be complete it must include connecting wires, a power source, and a load. The
power source provides coulombs with energy which is measured in joules. The coulombs decrease in
energy as they pass through the load, providing the load with energy to create light, heat or perform
some sort of action. The connecting wires create a path allowing the coulombs to flow through the
circuit. In a series circuit there is only one path along which coulombs can flow. The amount of
coulombs moving through a point in the circuit in a certain amount of time is referred to as the current.
Current is measured by an ammeter which is connected inside the circuit. Voltage (potential
difference) is the amount of energy per coulomb of charge across a certain point in a circuit. It is
measured by a voltmeter which is connected across two points in a circuit outside of the circuit
(connected in parallel).
Purpose:
PART A: To observe the effect of changing the resistance on the current in a series circuit.
PART B: To observe the effect of changing the voltage on the current in a series circuit.
Materials:
Ammeter
Wires
Power source
25  resistors
Switch
Light bulb
Methods:
*SAFETY CONCERNS*:
1. Make sure the switch is open before you connect the meters
2. Never raise the voltage above 10V
Use the following method to build each of the circuits required in this lab.
A) Each circuit requires: 1 switch, power source, wires, and the load indicated (ie. Light bulb,
resistor).
B) Open the switch before making the circuit.
C) Connect the ammeter into the circuit on the negative side of the power source. Make sure the
negative terminal of the ammeter is connected with the negative terminal of the source (black to
black).
D) Turn the power source on to the voltage indicated. Close the switch.
E) Measure the current with the ammeter. Record measurements in Table 1 (on page 3) for PART A
and Table 2 (on page 3) for PART B.
1
PART A – The effect of changing the resistance on the current in a series circuit
Experiment 1: Building a Circuit with a 25 ohm resistor
1. Make a circuit with a 25 ohm resistor. Follow steps A to E in Methods section.
2. Draw the circuit in the observations section and show which direction the current is flowing
(with arrows).
3. Touch the resistor (be careful!). Answer question 1 under qualitative observations.
4. Set the voltage on the power source to 10 V.
Experiment 2: Building a circuit with one light bulb
1. Make a circuit with one light bulb. Follow steps A to E in Methods section.
2. Draw the circuit in the observations section and show which direction the current is flowing
(with arrows).
3. Answer question 2 under qualitative observations.
4. Set the voltage on the power source to 10 V.
Experiment 3: Building a circuit with a light bulb and a resistor
1. Make a circuit with a light bulb and a resistor. Follow steps A to E in Methods section.
2. Draw the circuit in the observations section and show which direction the current is flowing
(with arrows).
3. Answer question 3 under qualitative observations.
4. Set the voltage on the power source to 10 V.
PART B– The effect of changing the voltage on the current in a series circuit
1. For PART B follow steps A to C in the Methods section to build a circuit with a light bulb.
2. Set the voltage to 3V
3. Follow steps D and E in the methods section
4. Change the voltage to 6V
5. Follow steps D and E in the methods section
6. Change the voltage to 10V
7. Follow steps D and E in the methods section.
8. Answer question 4 under qualitative observations.
2
Observations
Diagrams (PART A)
Series circuit with a 25 resistor Series circuit with a light bulb
Series circuit with light bulb and
25 resistor
Quantitative Observations:
Table 1: The effect of changing the ________________________ on the ____________________ of a
series circuit
Type of Load
Experiment 1- 25 resistor
Current (A)
Experiment 2- light bulb
Experiment 3- 25 resistor and light bulb
Table 2: The effect of changing the ________________________ on the ____________________ of a
series circuit
Voltage (V)
3
Current (A)
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Qualitative Observations:
Answer the following questions using full sentences and don’t explain why here!
PART A
1. What did you notice about the resistor when you touched it?
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2. What happens to the light bulb when the switch is closed?
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3. How does the brightness of the bulb in experiment 3 circuit compare to the brightness of the
bulb in experiment 2?
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PART B
4. What happened to the brightness of the bulb when voltage was increased?
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Discussion
Answer these questions in several paragraphs (at least one per question). Be as specific as possible in
your explanations!!
5. Explain your qualitative observations of the resistor and the light bulb in PART A. What is
happening to the electrical energy as it moves through each type of load? Why does adding the
25 ohm resistor to the circuit with the bulb affect the bulb’s brightness?
6. Explain your qualitative observation from PART B. How does increasing the voltage in the
circuit affect the bulb’s brightness?
7. Using your quantitative values in Table 1, make a conclusion about how current changes when
the resistance in a circuit is increased. Explain why this is true using Ohm’s Law.
8. Using your quantitative values in Table 2, make a conclusion about how current changes when
the voltage of the power source is increased. Explain why this is true using Ohm’s Law.
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(Continue on lined paper if needed)
5
SNC 1D- Lab Marking Scheme
Sections
Level 1
Minimal
requirements
are met
Level 2
Some of the
requirements
are met
Level 3
Most of the
requirements
are met
Level 4
All of the
requirements
are met
Weight
Inquiry
Qualitative observations
made are clear and detailed
2x
Discussion
Qualitative observations
from PART A are explained
fully
Discussion
Qualitative observations
from PART B are explained
fully
Discussion
Conclusions about the effect
of changing resistance on
current are well explained
Discussion
Conclusions about effect of
changing voltage on current
are well explained
2x
2x
3x
3x
/48
Overall Inquiry
Communication
2x
Data Table 1 and 2
All values are included and
are clearly written
Diagrams
Include all components
involved in the circuit and
show movement of electrons
Spelling and grammar (used
full sentences)
2x
1x
/20
Overall Inquiry
6