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Using a simple pendulum experiment g is determined by measuring its time period T. Which of the following plots represent the correct relation between the pendulum length L and time period T?

Asked in JEE Main 22nd Jan 1st Shift 2026 · Reading the pendulum graphs

• (1) A curve of 1/T² against L that starts high and falls steeply to zero, concave downwards
• (2) A straight line of 1/T² against L with negative slope
• (3) A rectangular hyperbola: 1/T² against L falling steeply at first and then flattening towards the axis
• (4) A curve of 1/T² against L that rises with increasing steepness

Step-by-step solution

Why the other options are wrong

• (1) comes from a curve that meets the L axis at a finite length, which would mean the period becomes infinite for a pendulum of ordinary length
• (2) comes from reading 1/T²∝ L as a straight line without noticing that the relation is a reciprocal one, not a linear one
• (4) comes from the shape of T² against L, which does rise; the axis here is 1/T², so the curve must fall

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