Observations

1: From the measured values of circuit current and supply voltage calculate the equivalent circuit resistance

R_EQ= Ω

2: Compare the values of equivalent circuit resistance from the previously measured value and the calculated value above

Measured R_EQ= Ω

Calculated R_EQ= Ω

The two values are

3: Add the two measured values of voltage drop U_R1 and U_R2//R3

U_R1V + U_R2//R3V = V

Did the two values sum to equal the supply voltage U_S

4: Add the two measured values of parallel branch currents I_R2 and I_R3

I_R2A + I_R3A = A

Did the two values sum to equal the supply current I_S

5: What would be the result of a short circuit across resistor R₃.

R_EQ= Ω

I_S= A

The equivalent resistance

6: What would be the result of an open circuit in resistor R₃.

R_EQ= Ω

I_S= A

The equivalent resistance

2: Connect the following series parallel circuit and complete the table below by measuring the required parameters.

Supply voltage = 22V 

Ensure the current limit on the power supply is set to a maximum of 5A  (ask your teacher how, if you are unsure)

R1 = 5Ω

R2=10Ω

R3=15Ω

Calculate the circuit R_EQ = Ω

Using the circuit above, open circuit resistor R₃ by disconnecting one of the R₃ leads

What was the resulting circuit current A

The circuit current

Using the circuit above, short circuit resistor R1 by placing a connection lead across both of the R1 terminals

What was the resulting circuit current A

The circuit current

Skill Practice:      Series Parallel Circuits

 Task

To connect resistors in series and parallel combination and to examine the current, voltage and resistance relationships in series parallel circuits.

Objectives

At the completion of this exercise you should able to: 

1. connect a series parallel circuit using a circuit diagram as a guide
2. use a multimeter as an ohmmeter to measure resistance values
3. observe the effects of open circuit and short circuit on series parallel circuit resistance values
4. measure and record voltage and current values of a series parallelcircuit
5. verify the laws of series parallel circuits
6. apply Ohm's Law to verify circuit parameter relationships in series parallelcircuits

Equipment Required

Your teacher will provide you with the specifications of the equipment to be used. 

• DC power supply
• Digital multimeter
• Voltmeter
• Ammeter
• Analog multimeter
• Single pole switch
• Fuse
• Resistors

• 5 Ω, 30 W
• 10 Ω, 30 W
• 15 Ω, 30 W

Procedure

 Using and Analog and a Digital multimeter measure and record the resistance of R1, R2 and R3 including various combinations of the resistors connected in series parallel as identified below.

Task 7 – Deal with Unplanned Events

This task

requires you to describe suitable methods for dealing with unplanned events or unexpected

situations.

Scenario:

During this

assessment, you are measuring the circuit current as specified in Task 3.

You

notice that one of the resistors begins to emit smoke because it's power rating has been exceeded.

What corrective actions should you take?

Task 6 – Modify existing circuit to comply with specified operating parameters.

The total current in the circuit needs to be reduced to approximately 50% of the original value. This will be done by changing the value of resistor R2.

Calculate:

1. the value of the replacement resistor - R NEW

50% of existing current

show your working here 

Answer. = mA

New Total circuit resistance

show your working here 

Answer. = Ω

New replacement for R2 = RT - (R1+R3)

show your working here 

Answer. = Ω

2. the new total power dissipated by the circuit - PT NEW

show your working here 

Answer. = W

Use an ohmmeter to find a suitable replacement resistor from those provided. replace R2 and check your selection by building the circuit and measuring the circuit current.

Measured circuit current matches that in Q1.  = mA

Task 5 – Calculate unknown circuit parameters from measured values.

From the measured values in Task 4, determine the following circuit parameters by calculation.

1. Actual total resistance of resistors in series (R1 + R2 + R3) from measured results.

show your working here 

Answer. = Ω

2. Actual value of R1  from measured results.

show your working here 

Answer. = Ω

3. Actual value of R2  from measured results.

show your working here 

Answer. = Ω

4. Actual value of R3  from measured results.

show your working here 

Answer. = Ω

5. Total power dissipated by the circuit (PT).  from measured results.

show your working here 

Answer. = W

6. Measured value of R1 using an ohmmeter

Answer. = Ω

7. Measured value of R2 using an ohmmeter

Answer. = Ω

7. Measured value of R3 using an ohmmeter

Answer. = Ω

Task 4 – Energise the DC circuit and take electrical measurements.

Switch on the power supply and adjust the output voltage to 20 volts. Measure the circuit parameters listed below and record your readings in the spaces provided

• Work within established safety procedures

• Accurately measure and record the circuit current

Your teacher will confirm your competency in each item listed above in the Skill Assessment checklist.

Adjust the power supply to 20V and record the following:

Switch open I _Supply = mA

Switch Closed I _Supply = mA

U_R1 = V

U_R2 = V

U_R3 = V

Task 2: Draw a single path DC circuit.

On a clean piece pf paper, draw a circuit diagram of a DC series circuit consisting of two loads;

• a fuse labelled F1 to protect ALL equipment in the circuit (including meters)
• a single pole switch labelled S1 that controls the circuit
• three resistors labelled R1-10Ω, R2-5Ω and R3-20Ω
• an ammeter to measure total circuit current (show correct meter polarity)
• a voltmeter to measure supply voltage (show correct meter polarity)

Up load your drawing here. once you have completed all tasks and you teacher has signed your drawing.

Task 1 – Complete a Risk Assessment

Hierarchy of Control

The recommended code of practice outlines six steps for selecting the hierarchy of control.

When assessing potential solutions to reduce the potential of accidents, start with the first step and work your way through each option.

Following are the steps in order of application:

1: Elimination

2: Substitution

3: Isolation

4: Engineering

5: Administrative

6: Personal protective equipment.

Task 8 – Work Completion

This task requires you to perform work completion tasks according to safe work procedures. You will be assessed on your ability to:

• Follow OHS risk control measures and procedures when completing work

• Minimise waste and ensure sustainability

• Follow correct procedures in completion of the task, including documentation and notification

• Connect the circuit accurately using appropriate tools and equipment, whilst ensuring no damage to apparatus, circuits and the surrounding environment or services.

Work Completion Checklist

Populate the table below to identify all the completed tasks: