🌈 Rainbow mind map and MCQ of Length

Physics • Measurement • Interactive Learning

Rainbow 🌈 Mind Map: Length

Understand length, measurement units, least count and indirect measurement methods—then test yourself with an interactive MCQ quiz.

🌈Length at a Glance

Length tells us how far apart two points are. It is one of the seven SI base quantities.

Definition

Length is the distance between two points.

Type of Quantity

Length is a fundamental or base physical quantity.

Units

CGS: centimetre (cm)
MKS and SI: metre (m)
FPS: foot (ft)

Useful Relations

1 m = 100 cm1 ft = 30.48 cm

Multiple Units

Hectometre (hm) and kilometre (km) are larger units of length.

Submultiple Units

Decimetre (dm), centimetre (cm) and millimetre (mm) are smaller units.

📏Common Measuring Devices

The least count is the smallest measurement that an instrument can reliably read.

Instrument	Common Use	Typical Least Count
Ruler / metre scale	Everyday lengths and straight distances	1 mm = 0.1 cm
Vernier calipers	Internal diameter, external diameter and depth	0.1 mm = 0.01 cm
Screw gauge	Very small thicknesses and diameters	0.01 mm = 0.001 cm

🔁Live Length Converter

Enter a value, select the units and see the converted answer instantly.

Value

From Kilometre (km) Metre (m) Centimetre (cm) Millimetre (mm) Foot (ft) Inch (in)

To Kilometre (km) Metre (m) Centimetre (cm) Millimetre (mm) Foot (ft) Inch (in)

1 m = 100 cm

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🧪Indirect Measurements

When an object cannot be measured directly with a ruler, we use a suitable indirect method.

1. Diameter of a Sphere

Place the sphere between two vertical blocks. Measure the distance between the inner faces of the blocks.

2. Length of a Curve

Lay a thread carefully along the curve, mark its endpoints, straighten it and measure it with a ruler.

3. Thickness of a Coin

Stack ten similar coins, measure the total thickness and divide the result by 10.

Thickness of one coin = Total thickness ÷ Number of coins

4. Thickness of a Wire

Wind the wire tightly in adjacent turns around a pencil. Measure the width of the turns and divide by the number of turns.

Wire diameter = Width of turns ÷ Number of turns

🧠Rainbow MCQ Quiz: Length

Select one option and press Check Answer. Your score updates after each question.

0/7

1. Length is the distance between:

A) Two lines B) Two points C) Two cities D) Two countries

2. Length is a:

A) Vector quantity B) Derived quantity C) Fundamental quantity D) Non-physical quantity

3. The SI unit of length is:

A) Centimetre B) Foot C) Metre D) Kilometre

4. 1.5 metres is equal to:

A) 15 cm B) 1,500 cm C) 15,000 cm D) 150 cm

5. 56.2 kilometres is equal to:

A) 56,200 m B) 562 m C) 562,000 m D) 5,620 m

6. The least count of a standard ruler is usually:

A) 1 mm B) 1 cm C) 0.01 cm D) 0.1 mm

7. To find the thickness of one coin from a stack of 10 similar coins, we should:

A) Divide the thickness of 10 coins by 10 B) Add 10 to the total thickness C) Subtract 10 from the total thickness D) Multiply the total thickness by 10

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❓Frequently Asked Questions

Length is the distance between two points. It is a fundamental physical quantity.

The SI unit of length is the metre, written with the symbol m.

Least count is the smallest value that a measuring instrument can read accurately.

Place a thread along the curve, mark its endpoints, straighten the thread and measure it with a ruler.

Stack several similar coins, measure their total thickness and divide by the number of coins.

There are 100 centimetres in one metre.

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Concept by Teacher Ritu • Designed by Shaleen Shekhar • Speed Up Science