Soldering Techniques
What is the first step before applying solder to a joint?
Tin the wire or component
What is the formula for calculating the total resistance in a series circuit?
R_total = R1 + R2 + R3..
What is the purpose of a resistor color code?
To indicate the resistor's value
What should you do immediately after finishing soldering?
Turn off and clean the soldering station
What is the formula for calculating total capacitance in a parallel circuit?
C_total = C1 + C2 + C3.
In a parallel circuit, if one branch has a resistance of 10 ohms and another branch has a resistance of 20 ohms, what is the total resistance?
(R_total = 1 / [(1/10) + (1/20)] = 6.67 ohms)
What material is commonly used to clean the tip of a soldering iron?
Wet sponge or brass wool
If the resistance is 10 ohms and the current is 2 amps, what is the voltage across the resistor using Ohm's Law?
Voltage = 20 volts; V = IR Multimeter
What component stores energy in a magnetic field?
Inductor
What safety precaution must be taken before working on a live circuit?
Remove power and ensure tools are insulated
A circuit has a voltage of 120V and a current of 3A. What is the power consumed?
Power = Voltage × Current; Power = 360 Watts
In a series circuit with a 5-ohm resistor, a 10-ohm resistor, and a 15-ohm resistor, what is the total resistance?
R_total = R1 + R2 + R3; R_total = 30 ohms
Which solder type melts at a higher temperature: Lead or Lead-free?
Lead-free solder
How is the period of a waveform calculated if its frequency is 50 Hz?
Period = 1/Frequency; Period = 0.02 seconds) Electrical waveforms
What is the key characteristic of a polarized capacitor?
It must be connected in the correct orientation
What must you do if a component moves during soldering?
Re-solder to avoid a cold joint
A series circuit has three resistors with values of 100 ohms, 220 ohms, and 330 ohms. What is the total resistance?
R_total = R1 + R2 + R3; R_total = 650 ohms
A combination circuit has a 10-ohm and 20-ohm resistor in parallel, connected in series to a 5-ohm resistor. What is the total resistance?
Parallel: 1 / [(1/10) + (1/20)] = 6.67 ohms. Total = 6.67 + 5 = 11.67 ohms
What does "ROHS-compliant solder" indicate?
It is lead-free and environmentally friendly
What is the power dissipated by a resistor with a resistance of 5 ohms when the current through it is 3 amps?
Power = I²R; Power = 45 watts
What does the base of a bipolar transistor control?
The flow of current between the collector and emitter
Why is it important to read the lab's Safety Data Sheets?
To understand the risks and handling of chemicals
In a series circuit with a voltage source of 12V and three resistors of 2 ohms, 3 ohms, and 5 ohms, what is the total current flowing through the circuit?
I = V / R_total; R_total = 2 + 3 + 5 = 10 ohms. I = 12V / 10 ohms = 1.2A
In a parallel circuit with three branches, where each branch carries 2A of current, what is the total current supplied by the source?
I_total = I1 + I2 + I3; I_total = 2A + 2A + 2A = 6A
Name one tool used for stabilizing small parts while soldering.
Helping Hands
A resistor has color bands of red, violet, and brown. What is its resistance value in ohms?
Resistance = 270 ohms; Red = 2, Violet = 7, Brown = Multiplier of 10
What happens when a transformer has the same number of turns on primary and secondary sides?
It isolates circuits without changing voltage
What tool is critical for assembling circuits during lab work?
Schematic diagrams
A circuit consists of a 12-ohm resistor and a 24-ohm resistor in parallel, connected in series to a 6-ohm resistor. What is the total resistance?
Parallel: 1 / [(1/12) + (1/24)] = 8 ohms. Total R = 8 + 6 = 14 ohms
In a combination circuit, a 100-ohm resistor is in series with a parallel network of two 200-ohm resistors. What is the total resistance?
Parallel: 1 / [(1/200) + (1/200)] = 100 ohms. Total = 100 + 100 = 200 ohms