220-1101 Mobile Devices Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Multimeter: Measure voltage, resistance, and continuity

  Why this is correct

  A multimeter measures electrical properties in a computer's power supply and circuits: AC/DC voltage, resistance in ohms, and continuity via an audible tone. It is essential for diagnosing dead motherboards, faulty PSUs, and shorted or open traces by comparing readings against expected values. Always set the proper range and function before probing live connections to avoid damage.

• ✓

  Compressed air: Blow away dust and debris from components

  Why this is correct

  Compressed air dislodges dust and debris from heat sinks, fans, and power supplies, preventing thermal buildup and mechanical failure. Hold fans stationary with a finger to stop high-speed spinning that can generate back-EMF and damage the motor or motherboard. Use short bursts at an angle to avoid forcing contaminants deeper into tight spaces.

• ✓

  Antistatic wrist strap: Prevent electrostatic discharge damage

  Why this is correct

  An antistatic wrist strap connects your body to chassis ground via an alligator clip and a 1MΩ resistor, neutralizing static charge differences. This prevents electrostatic discharge (ESD) from damaging sensitive solid-state components like RAM modules, CPU sockets, and expansion cards. The resistor ensures safety by limiting current if you accidentally touch live voltage.

• ✓

  Thermal paste: Improve heat transfer between CPU and heatsink

  Why this is correct

  Thermal paste fills microscopic pits and grooves on the CPU's integrated heat spreader and the heatsink base, creating a continuous path for heat conduction. Without it, air gaps act as thermal insulators, causing the CPU to overheat and throttle or fail. Apply a pea-sized drop in the center; mounting pressure spreads it evenly without creating bubbles or overflow.

• ✗

  Multimeter: Remove dust from components

  Why it's wrong here

  A multimeter is an electronic test instrument, not a cleaning device; using it to remove dust would damage its probes, LCD, and internal components. Dust removal is performed with compressed air or an anti-static brush, not with electrical probes. This option confuses the multimeter's role of measuring voltage, resistance, and continuity with that of a pneumatic cleaning tool.

• ✗

  Compressed air: Measure electrical values

  Why it's wrong here

  Compressed air has no way to measure voltage, resistance, or continuity because it lacks sensing elements, a display, and a power source for readings. Measuring electrical values requires a multimeter with probes connected to a circuit. Compressed air's sole purpose in PC repair is to blow away contaminants, so pairing it with electrical measurement is a categorical mismatch.