NCERT Solutions Class 11 Engineering Graphics Chapter 2 PDF

Concept used. A technical drawing is read by line convention. The line type tells the reader whether the feature is visible, hidden, central, dimensional or broken.

1. For the axis of a cone, use a centre line. It is a thin chain line made with long and short dashes.
2. For a boundary line, use a continuous thick line. It shows the drawing sheet boundary or visible outline.
3. For a projection line, use a thin continuous line. It carries the projected size or position from the object.
4. For a short break, use a thin freehand curved line. It shows a small interrupted portion.
5. For a long break, use a thin straight line with spaced zigzags. It shortens a long uniform part.
6. For a dimension line, use a thin continuous line with arrowheads at the ends.

Concept used. Coinciding lines are different drawing lines that occupy the same location. A priority rule prevents confusing double drawing.

1. Sometimes a visible outline, hidden line and centre line may fall on the same path.
2. If all are drawn together, the drawing becomes unclear.
3. The highest-priority line is drawn first and read as the main line at that position.
4. NCERT gives the order as continuous thick line, hidden line and centre or axis line.

Concept used. Computer Aided Design means designing and drawing with the help of a computer instead of only manual instruments.

1. The full form of CAD is Computer Aided Design.
2. A CAD program helps the user draw lines, arcs, circles, dimensions and symbols accurately.
3. It also helps modify a drawing without redrawing the whole sheet.
4. CAD files can be stored, printed, shared and reused.
5. In engineering work, CAD reduces manual repetition and improves accuracy.

Concept used. A digital drawing can be corrected, copied, scaled and stored without starting again on a fresh sheet.

1. CAD saves time because changes can be made directly in the file.
2. It saves labour because repeated shapes, symbols and dimensions can be copied or reused.
3. It improves accuracy, so fewer drawings need to be remade because of mistakes.
4. It saves paper because trial versions can be checked on screen.
5. It also saves storage space because many drawings can be kept digitally.

Concept used. A language needs signs that others can understand. Engineering Graphics uses graphic signs instead of spoken words.

1. The chapter calls Engineering Graphics the universal language of engineers.
2. Engineers use it to communicate shape, size, position and technical ideas.
3. Its script includes lines, symbols and standard conventions.
4. It also uses letters, numerals and dimensions to complete the information.

Concept used. Line conventions are memorised by linking the purpose of the line with its appearance.

1. Axis line is drawn as a thin centre line.
2. Visible outline is shown graphically as a thick line.
3. Short break line is shown as a curved thin line.
4. Long break line is shown as a thin straight line with zigzags.
5. Hatching line is shown as thin continuous lines at 45^∘.

Concept used. Angles are classified by their measure or by their relation with another angle.

1. An acute angle is less than 90^∘.
2. A right angle is exactly 90^∘.
3. An obtuse angle is more than 90^∘ but less than 180^∘.
4. A straight angle is 180^∘.
5. A reflex angle is more than 180^∘ but less than 360^∘.
6. Adjacent angles lie on either side of a common arm.
7. Complementary angles add to 90^∘.
8. Supplementary angles add to 180^∘.

Concept used. A technical drawing needs written information as well as geometry. Lettering makes that information readable.

1. Letter printing is the standard writing of letters and numerals.
2. It is used for titles, sub-titles, notes, dimensions and labels.
3. The letters should be clear, uniform and legible.
4. They should have proper height, width, thickness and spacing.
5. In Engineering Graphics, neat lettering is part of the drawing standard.

Concept used. Single stroke lettering means each stroke is drawn once with uniform thickness.

1. Use guide lines so that the height remains uniform.
2. Write each stroke once. Do not sketch repeatedly over the same line.
3. Keep all letters uniform in shape, size, stroke and spacing.
4. Keep the same shine and darkness in letters and numerals.
5. Maintain proper gaps between letters and between words.
6. Remove unnecessary guide lines after the lettering is complete.

Concept used. Proportion means the relation between height and width. Spacing means the clear gap between letters and words.

1. Capital letters should look uniform in height and width.
2. Most capital letters follow an approximate height-to-width proportion of 5:3.
3. Letters such as I and J are narrower, while M and W are wider.
4. Small letters are divided into body height, ascenders and descenders.
5. The gap between two letters may be about twice the stroke thickness.
6. The gap between two words may be about the width of one letter.

Concept used. Each instrument controls one part of drawing accuracy: support, measurement, line direction, circle construction or sheet cleanliness.

1. A drawing board gives a smooth working surface.
2. Drawing sheets carry the final drawing.
3. Pencils such as HB, 2H and 4H produce different line qualities.
4. A scale measures and draws straight lengths.
5. A compass draws circles and arcs.
6. A divider transfers distances and divides a line into equal parts.
7. Set squares draw vertical, inclined and parallel lines.
8. A protractor measures and marks angles.
9. A T-square, roller or mini drafter helps draw horizontal, vertical and parallel lines.
10. Eraser, erasing shield, clips and cloth help keep the sheet clean.

Concept used. A technical drawing must show not only shape but also exact size. Dimensioning gives that size information.

1. Dimensioning means writing a numerical measurement on a technical drawing.
2. In this chapter, dimensions are normally expressed in millimetres.
3. Dimension lines are thin continuous lines terminated by arrowheads.
4. Extension or projection lines extend from the outline to the dimension line.
5. Leader lines connect a note or dimension figure to a feature.
6. Arrowheads touch the outline, extension line or centre line.
7. The dimension figure gives the measured value.
8. Common symbols are R for radius, diameter symbol for diameter and square symbol for square.

\CTAButton{\CTAUrlBookpdf}{Download the Full NCERT Book Chapter PDF} \RelatedResources