CHERM_ Second Term Examination 2082_ Solution

Shree Secondary School Dudhiawa

Phatuwa Bijaypur -10, Rautahat

Half-yearly Examination 2082

Subject: Computer Hardware, Electronics, Repair & Maintenance

Class: X (Technical)                                         Time: 2:00                              Full Marks: 50

Group A: Write best answers in your answer sheet          [9X1=9]

1.     The force of attraction between molecules is called:

A. Magnetic force                                 B. Electrostatic force         

C. Intermolecular force        D. Nuclear force

2.     If an atom loses one electron during bonding, its charge becomes:

A. Neutral                       B. Positive               C. Negative              D. Zero

3.     The device that converts human-readable data into machine-readable data is called:

A. Output unit     B. Input unit           C. Printer      D. Memory unit

4.     Which display technology uses electron beams hitting a phosphor screen?

A. LCD                 B. LED                        C. CRT                      D. Plasma

5.      A computer with low resolution will display:

A. More pixels                           B. Fewer pixels
C. Higher refresh rate              D. Brighter images

6.     Which file system is commonly used by Windows?

A. HFS+               B. Ext4                       C. NTFS        D. FAT12

7.      Why do power supplies use rectifiers?

A. Convert AC to DC              B. Store energy
C. Increase heat output                       D. Slow down current

8.      What should be checked first during troubleshooting?
A. The most advanced settings                                  B. The motherboard
C.  The most general possible problems            D.  Windows registry

9.      Which of the following is part of hardware troubleshooting?
A. Editing a Word file                                      B. Updating social media
C. Removing or replacing faulty RAM    D. Changing wallpaper

Group B: Give short answers to any five questions          [5X5=25]

10. What is the main difference between primary memory and secondary memory?

Primary Memory	Secondary Memory
It is a Volatile (loses data on power off)	It is a Non-volatile (retains data)
It is Very fast and direct accessible by CPU	It is Slower and accessed via I/O channels
These are Small in storage size (GBs)	These are Large in storage size(TBs)
It is Expensive per GB	It is Cheaper per GB
Example: RAM, Cache	Example HDD, SSD, USB

 

11. What is color depth? Why is it important for display quality?

Color depth is the number of bits used to represent the color of each pixel on a display, determining how many distinct colors it can show. Each pixel on a screen can display a color, and the color depth defines how many colors are possible.

Color depth is important for display quality because Higher color depth allows smoother gradients and more accurate colors and more colors make images, videos, and graphics look more natural and closer to real life. Low color depth can cause visible color steps (banding), especially in gradients; higher depth reduces this issue.

 

12. Distinguish between raster scan and random scan displays.

 

Raster Scan Display	Random Scan Display
Scans the screen line by line (horizontal rows) from top to bottom.	Draws images by directly moving the electron beam to the lines that form the object (vector drawing).
Best for images, photographs, and full-screen graphics.	Best for line drawings, charts, and diagrams.
Needs a constant refresh of the entire screen.	Refreshes only the lines being drawn, not the entire screen.
Requires a frame buffer to store the image.	Requires a vector generator; no full-frame buffer needed.
Simpler and cheaper to implement.	More complex and expensive due to vector generator.
Can display complex images, but may have limited resolution based on pixels.	Produces high-quality line images, very sharp.
May flicker for high-resolution screens if refresh rate is low.	Less flicker because only necessary lines are drawn.

 

13. What is cache memory?

Cache Memory is a small, high-speed memory located inside or very close to the CPU. It is used to temporarily store frequently accessed data and instructions. The core purpose of cache memory to speed up data access for the CPU.

14. List out the types of semiconductors. Describe briefly about the formation of N-Type semiconductor.

A semiconductor is a material that partially conducts electricity, not as well as a conductor but better than an insulator. Its conductivity can be controlled by temperature, light, or by adding impurities (doping).

Following are the types of Semiconductors

1.       Intrinsic Semiconductor:  It is Pure semiconductor with no impurities. Example: Pure silicon (Si), pure germanium (Ge).

2.      Extrinsic Semiconductor: It is a Semiconductor whose conductivity is improved by adding impurities (doping).  Its Two types are ; N-Type Semiconductor and P-Type Semiconductor.

N-type semiconductors form by doping pure silicon or germanium with pentavalent impurities like phosphorus, arsenic, or antimony.

These impurities have five valence electrons. Four bonds with the semiconductor lattice, leaving the fifth as a free electron in the conduction band. This creates excess mobile electrons as majority charge carriers.

The material gains negative charge carriers (hence "N-type"), enabling better conductivity for diodes and transistors. Donor energy levels sit just below the conduction band.

15. Why is the CPU referred to as the “brain of the computer”?

The CPU is called the "brain of the computer" because it controls all operations, processes instructions, performs calculations, and coordinates other hardware components like memory and input/output devices.

It fetches, decodes, and executes program instructions through its arithmetic logic unit (ALU) and control unit, managing data flow similar to how the human brain directs body functions. Without the CPU, the system cannot process tasks or respond to inputs.

16. What does POST stand for in computer booting?

During computer booting, POST is a diagnostic routine run by the BIOS/UEFI right after power-on. It checks critical hardware like CPU, RAM, storage, and peripherals to ensure everything functions before loading the operating system.

If tests pass, booting continues silently. Failures trigger beep codes, error messages, or LED patterns to indicate issues like bad RAM or no keyboard.

 

Group C: Give long answers to any two questions            [2X8=16]

 

17. Explain the meaning of troubleshooting and describe the difference between hardware and software troubleshooting with examples.

Troubleshooting means finding and fixing problems in a computer or device using a step-by-step process, starting with simple checks and getting more specific.

In other words, Troubleshooting is the process or identifying and fixing problems that may involve hardware or software and can sometimes involve both at the same time.

Following are the differences between Hardware and software troubleshooting.

Hardware Troubleshooting	Software Troubleshooting
It is targeted on Physical components (RAM, cables, drives)	It is targeted on Programs, OS, settings
Its symptoms may be No power, beeps, crashes, overheating	Its symptoms may be Slow speed, error messages, freezes
The tools needed are Screwdriver, multimeter, diagnostic LEDs	The tools needed are Task Manager, safe mode, antivirus
The first step is Power cycle, visual inspection	The first step is Restart computer, close programs
The risk level May void warranty, physical damage	The risk level is Usually safe, backup recommended
Examples: Check power cord, reseat RAM, clean dust	Examples: Restart app, update software, scan viruses

 

18. State and explain Kirchhoff’s Current Law (KCL). Provide an example of a simple circuit showing how KCL is applied at a node.

Kirchhoff’s Current Law (KCL) State that at any node (junction) in a circuit, the total current flowing into the node is equal to the total current flowing out of the node. This is based on conservation of charge: no charge is lost or created at the junction i.e. Sum of currents entering a node = sum of currents leaving the node.

In equation form, if currents entering are taken as positive and leaving as negative, then the algebraic sum at a node is zero i.e. .

Example Circuit and Application

In the given figure, currents I1 and I2 are entering to the node while the currents I3 and I4 are leaving from the node. By applying KCL at the node, assume that entering currents are positive and leaving currents are negative, we can write as

I1 + I2 + (-I3) + (-I4) = 0

I1 + I2 = I3 + I4

19. Explain the functions of the CPU. Describe the roles of the ALU and Control Unit.

The main function of CPU is to executes instructions, performs calculations, manages data flow, and coordinates hardware components through its fetch-decode-execute cycle.

The role of Arithmetic Logic Unit (ALU) is to handle all mathematical operations (add, subtract, multiply) and logical decisions (AND, OR, comparisons). It processes raw data from registers to produce results.

    The role of Control Unit is to direct/instruct operations by fetching instructions from             memory, decoding them, and signaling other parts (such as ALU, registers, I/O) to act. It     acts like a traffic controller for timing and sequence.