Q.A machine costing ₹50,000 depreciates at a constant rate of 8%. What is the depreciation charge for the 8th year. If the estimated useful life of the machine is 10 years, determine its scrap value.

Straight Line Depreciation: The Intuition

Imagine you buy a delivery van for your business. It costs ₹10,00,000. You expect to use it for 5 years, after which you'll sell it for ₹1,00,000 as scrap.

Does the van lose all its value in year 1? No. It loses value gradually, year after year, as you drive it, put miles on it, and it gets older. The van is an asset — something of value you own — and its value decreases over time. That decrease is called depreciation.

The simplest way to think about this loss is: the van loses the same amount of value every year. That's straight line depreciation. It's like slicing a cake into equal pieces — each year gets an equal share of the total loss in value.

The Precise Statement

Where:

• Cost of Asset = What you paid to buy and get it ready for use (purchase price + delivery + installation, etc.)
• Residual Value (also called scrap value or salvage value) = What you expect to get when you sell it at the end of its useful life
• Useful Life = How many years you expect to use the asset

Applying It to Our Van

Cost = ₹10,00,000

Residual Value = ₹1,00,000

Useful Life = 5 years

So every year, you record ₹1,80,000 as depreciation expense. After 5 years, the van's book value (original cost minus total depreciation) will be exactly ₹1,00,000 — its residual value.

The Depreciation Schedule

Notice: the depreciation expense is constant every year. That's the "straight line."

Why Use This Method? …