Lesson 1, Topic 1
In Progress

2EM 1.2 Exercise Question 5

The illumination, \(I\) units, of a bulb varies inversely as the square of the distance, \(d\) metres.
Given that the illumination is \(9\) units when the distance is \(2\)m,


express \(I\) in terms of \(d\),


find the percentage change in the illumination of the bulb which is required to reduce the distance of the bulb to \(\frac{1}{5}\) of its original value.

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