<p>A lamp follows \(I\propto1/d^2\).</p>
<ol class="abc-list"><li data-list-item-id="item-1791433029159-wblvj6kxu" data-list-item-path="item-1791433029159-wblvj6kxu"><div class="list-item-paragraph"><p>Find the percentage change in illumination when distance increases by \(25\%\).</p></div></li><li data-list-item-id="item-1791433042011-9odn2rm0y" data-list-item-path="item-1791433042011-9odn2rm0y"><div class="list-item-paragraph"><p>By what percentage must distance decrease to double the original illumination? Give your answer to \(1\) decimal place.</p></div></li></ol>

<p>Find the percentage change in illumination when distance increases by \(25\%\).</p>

<p>By what percentage must distance decrease to double the original illumination? Give your answer to \(1\) decimal place.</p>

Direct and Inverse Proportion

Direct and Inverse Proportion