OBJECTIVE TYPE QUESTIONS CAD and CAM

OBJECTIVE TYPE QUESTIONS CAD and CAM 

1.   Which two disciplines are tied by a common database?     

 CAD and CAM

2.   The term that is used for geometric modelling like solid modelling, wire frame modelling and drafting is known as

Software package                             

3.   The basic geometric building blocks provided in a CAD/CAM package are           

a) points                      b) lines                         c) circles                      d) all of the mentioned

4.   The life cycle of a product includes              
            a) extraction of natural resources                                            b) processing of raw materials
            c) manufacturing of products                                     d) all of the mentioned

5.   DBMS manages the interaction between __________ and database.
   End Users  

6.   A translation is applied to an object by
Re positioning it along with straight line path       

7.   To generate a rotation , we must specify
  Rotation angle ϴ    

8.   The transformation that is used to alter the size of an object is        
     Scaling                  

9.   What is the primary use of clipping in computer graphics?
   removing objects and lines           

10.         CAD/CAM is the relationship between
    design and manufacturing          

11.     The types of hidden surface removal algorithm are

                  a) Depth comparison, Z-buffer, back-face removal             b) Scan line algorithm, priority algorithm

c) BSP method, area subdivision method                              d) All of these

12.      Which co-ordinates allow common vector operations such as translation, rotation, scaling and perspective projection to be represented as a matrix by which the vector is multiplied?
       homogenous co-ordinates

13.                       The representation of complex objects which is not be drawn by wire frame model is called as
       Surface model    

14.                       The model which is created by using basic entities of two dimensioning is called __________
     Wire frame model

15.                       The __________ form the basis for surface models.
    solid model

16.                       The surface model is created by using ___________
 Analytic and Synthetic entities

17.                       The sweep representation of an object refers to the

3D representation

18.                       In the following geometric modelling techniques, which cannot be used for finite element analysis:
  None of the mentioned

19.                        In the following geometric primitives, which is not a solid entity of CSG modelling:
 Circle

20.                       The shape of the Bezier curve is controlled by:
 Control points

homogeneous transformation

 What is homogeneous transformation?

Homogeneous means a uniform representation of rotation, translation, scaling and other transformations.

A uniform representation allows for optimizations. 3D graphics hardware can be specialized to perform matrix multiplications on 4x4 matrices. It can even be specialized to recognize and save on multiplications by 0 or 1, because those are often used.

translation & scaling

Define translation & scaling

A translation moves an object to a different position on the screen. You can translate a point in 2D by adding translation coordinate (t_x, t_y) to the original coordinate (X, Y) to get the new coordinate (X’, Y’).

Scaling: To change the size of an object, scaling transformation is used. In the scaling process, you either expand or compress the dimensions of the object. Scaling can be achieved by multiplying the original coordinates of the object with the scaling factor to get the desired result.

Let us assume that the original coordinates are (X, Y), the scaling factors are (S_X, S_Y), and the produced coordinates are (X’, Y’). This can be mathematically represented as shown below −

X' = X . S_X and Y' = Y . S_Y

clipping, shading and colour

Clipping is a process of extracting a portion of a data base or identifying elements of a scene or picture inside or outside a specified region, called the clipping region


Shading is used in drawing for depicting levels of darkness on paper by applying media more densely or with a darker shade for darker areas, and less densely or with a lighter shade for lighter areas.


  Color model is a system for creating a full range of colours from a small set of primary colors. There are two types of colour models: additive and subtractive. Additive color models use light to display color, while subtractive color models use printing inks. The most common color models that graphic designers work with are the CMYK model for printing and the RGB model for computer display.

tools for CAM & CAM

CAD Tools AutoCAD, DesignCAD, Solidworks 3D CAD, Vectorworks, FreeCAD, Creo Parametric 3D Modeling Software, TurboCAD Deluxe 2018, Shapr3D, OpenSCAD, SolveSpace 


CAM Tools MASTERCAM, EMCO

Define CAD and CAM?

CAD means computer-aided design
  CAM means computer-aided manufacturing


 It is the technology concerned with the use of digital computers to perform certain functions in design and manufacturing.


 CAD can be defined as the use of computer systems to create, modify, analyze, or optimize an engineering design.


 CAM can be defined as the use of computer systems to plan, manage, and control the operations of a manufacturing plant through either direct or indirect computer interface with the plant’s production resources.

Differences between step index fibres and graded index fibres:

Step index fibre 

1. In step index fibres the refractive index of thecore medium is uniform through and undergoesan abrupt change at the interface of core and cladding.
 2. The diameter of core is about 50 to 200micrometers in case of multi mode and 10micrometers in single mode fibre
 3. The transmitted optical signal will cross thefibre axis during every reflection at the corecladding boundary.
 4. The shape of propagation of the optical signalis in zigzag manner.
5. Attenuation is more for multi mode step index fibres but Attenuation is less in single mode step index fibres
6. Numerical aperture is more for multi mode step index fibres but it is less in single mode step index fibres

  Graded index fibre
 1. In graded index fibres, the refractive index of the core medium is varying in the parabolic manner such that the maximum refractive indexis present at the center of the core.
 2. The diameter of the core is about 50 micro meters.
3. The transmitted optical signal will never cross the fibre axis at any time.
4. The shape of propagation of the optical signal appears in the helical or spiral manner
 5. Attenuation is very less in graded index fibres
 6. Numerical aperture is less in graded index fibres

Advantages of fibre optic communication

Advantages of fibre optic communication

The optical fibre communication has more advantages than convectional communication.
1. Enormous bandwidth
 2. low transmission loss
3. electric isolation
4. signal security
5. small size and less weight
6. low cost
7. immunity cross talk

  1. Enormous bandwidth
 The information carrying capacity of a transmission system is directly proportional to the frequency of the transmitted signals. In the coaxial cable (or convectional communication system) transmission the bandwidth range is up to around500MHZ. only. Where as in optical fibre communication, the bandwidth range is large as 105 GHZ.

2. Low transmission loss:- The transmission loss is very low in optical fibres (i.e. 1 2.0 − Km ) than compare with the convectional communication system. Hence for long distance communication fibres are preferred.

3. Electric isolation Since fibre optic materials are insulators, they do not exhibit earth and interface problems. Hence communicate through fibre even in electrically danger environment.

4. Signal security The transmitted signal through the fibre does not radiate, unlike the copper cables, a transmitted signal cannot be drawn from fibre with out tampering it. Thus the optical fibre communication provides 100% signal security.

 5. Small size and less weight The size of the fibre ranges from 10µm to50µm , which is very small. The space occupied by the fibre cable is negligibly small compared to convectional electrical cables. Optical fibres are light in weight.

  6. Low cost Since optical fibres made up of silica which is available in abundance, optical fibres are less expensive.

7. Immunity cross talk Since the optical fibres are dielectric wave guides, they are free from any electromagnetic interference and radio frequency interference. Since optical interference among different fibres is not possible, cross talk is negligible even many fibres are cabled together

Interference of light

The best evidence for the wave nature of light is interference phenomenon. This was experimentally demonstrated by Thomas Young in 180, through double slit experiment. Due to interference, we will observe many observations in our day today life, such as multiple colours on soap bubbles as well as on oil film when viewed under sun light. Interference concept is explained on the basis of superposition of wave’s concept. When two light waves superimpose, then the resultant amplitude or intensity in the region of superposition is different than the amplitude of individual waves

  Types of interference:- For the formation of interference pattern, two coherent light sources are required. To get two coherent sources form a single light source, two techniques are used. They are

 1. Division of wave fron
t
2. Division of amplitude

Division of wave front The wave front from a single light source is divided into two parts using the phenomenon of reflection, refraction, or diffraction. Young’s double slit experiment is belongs to this class of interference. Division of amplitude The amplitude of a single light beam is divided into two parts by parallel reflection or refraction. Newton’s ring experiment, Michelson’s interferometer is belongs to this class of interference.

  Conditions for interference

1) Two light sources of emitting light waves should be coherent.
 2) Two sources must emit continuous light waves of same wavelengths or frequency.
3) The separation between the two sources should be small.
4) The distance between the two sources and the screen should be large.
5) To view interference fringes, the background should be dark.
6) The amplitude of light waves should be equal or nearly equal.
7) The sources should be narrow.
 8) The sources should be monochromatic