Black Box Circuit Analysis - Measurements · RMPH 2013 #1
Physics · electromagnetism
Problem
In a black box are closed electric circuit elements such as: resistor, capacitor, diode, battery, and switches. YOU ARE NOT ALLOWED TO OPEN THE BLACK BOX!
Determine the type of black box circuit elements and how these elements are related to the four exterior contacts.
Available Equipment:
- An electrically conducting wire with plugs (negligible resistance)
- An electrical source: E=9V battery in series with a resistor having electrical resistance r=5.1kΩ (protective role)
- A stopwatch
- A multimeter (voltmeter measuring up to 20V)
- A black box with four connecting sockets (red, black, yellow, blue), a pressing switch (red button), and a three position switch (position 1 with green label, position 0 with red label)
Important Information:
- "Galvanic coupling" = electric connection of circuit elements
- "Optical coupling" = light emitted by one device induces modifications in another device (devices not electrically coupled)
- A diode exhibits low electrical resistance when forward biased, high resistance when reverse biased
- A light-emitting diode (LED) emits light when forward biased
- A photo resistor has electrical resistance that decreases when illuminated
- Inside the black box is a capacitor having capacitance C=4mFMeasurement Instructions:
- Press red button before each measurement
- Column A codes: 1 = connect electric source with positive (red) terminal to first terminal in column B; 2 = connect electric source with negative (black) terminal to first terminal in column B; 3 = connect terminals with wire; 4 = terminals remain free
- Measure voltages between terminal pairs, always connecting first terminal to COM (black) of voltmeter
- If voltage varies significantly over time, record pairs of (voltage, time) data
Task 1a: Perform measurements to complete table 1.1 with three-position switch in position 1.
Task 1b: Perform measurements to complete table 1.2 with three-position switch in position 0.
[Tables show voltage measurements between all terminal pairs (red-black, red-yellow, red-blue, black-yellow, black-blue, yellow-blue) for different connection configurations]