CMT Device Hardware & Software 3 — Questions and Answers
Question 1: What is the purpose of the IMEI number on a mobile device?
- It stores the user's SIM carrier profile
- It uniquely identifies the physical device on cellular networks (Correct answer)
- It encodes the device's Wi-Fi MAC address
- It tracks the device's software version history
Correct answer: It uniquely identifies the physical device on cellular networks
The IMEI (International Mobile Equipment Identity) is a 15-digit number that uniquely identifies a mobile device on cellular networks.
Question 2: A smartphone's GPS is inaccurate indoors but accurate outdoors. What is the most likely explanation?
- Faulty GPS antenna requiring replacement
- GPS relies on line-of-sight to satellites and is blocked by structures (Correct answer)
- The device OS needs a factory reset
- Cellular data is disabled, cutting off GPS
Correct answer: GPS relies on line-of-sight to satellites and is blocked by structures
GPS signals from satellites cannot penetrate most building materials, so indoor accuracy is naturally poor without assisted GPS (A-GPS) via Wi-Fi or cell data.
Question 3: Which storage interface standard offers faster read/write speeds on modern flagship smartphones compared to eMMC?
- microSD
- UFS (Universal Flash Storage) (Correct answer)
- NFC
- USB 2.0
Correct answer: UFS (Universal Flash Storage)
UFS (Universal Flash Storage) uses a serial full-duplex interface enabling simultaneous reads and writes, significantly outperforming eMMC.
Question 4: After installing a third-party screen protector, a customer reports Face ID no longer works. What is the most likely cause?
- The protector interfered with the earpiece speaker
- The protector is blocking the TrueDepth camera or IR sensor (Correct answer)
- Face ID data was wiped during installation
- The proximity sensor rebooted the device
Correct answer: The protector is blocking the TrueDepth camera or IR sensor
Face ID depends on the TrueDepth camera system and IR sensors; a protector covering or reflecting IR light prevents accurate face mapping.
Question 5: A technician notices swelling in a lithium-ion battery during a repair. What is the correct action?
- Puncture the battery to release gas safely
- Charge the battery to full before disposal
- Safely remove the battery and follow hazardous materials disposal procedures (Correct answer)
- Reinstall the battery and inform the customer
Correct answer: Safely remove the battery and follow hazardous materials disposal procedures
A swollen Li-ion battery has dangerous gas buildup and must be carefully removed and disposed of through proper hazardous/e-waste channels.
Question 6: What does 'bootloader unlocking' allow a technician or advanced user to do on an Android device?
- Bypass SIM carrier lock restrictions
- Install unofficial operating systems or custom firmware (Correct answer)
- Enable fast charging at higher wattage
- Access hidden diagnostic menus without a code
Correct answer: Install unofficial operating systems or custom firmware
Unlocking the bootloader removes the signature verification check, allowing installation of custom ROMs or unofficial OS builds.
Question 7: A device randomly restarts under heavy load. Which component is the most likely culprit?
- Front camera lens
- Battery unable to supply sufficient current under load (Correct answer)
- NFC chip overheating
- Fingerprint sensor firmware
Correct answer: Battery unable to supply sufficient current under load
A degraded battery with high internal resistance drops voltage sharply under heavy CPU/GPU load, triggering an automatic shutdown or restart.
CMT Device Hardware & Software 3
What is the purpose of the IMEI number on a mobile device?