Question

A bulb is hanging over a table. At which portion of the table is the illuminance maximum? If a plane mirror is placed above the bulb facing the table, will the illuminance on the table increase?

Answer 1

Explanation:

• Over a table, when a bulb is hanging, on the area just below the bulb, there will be the maximum illuminance, but the illuminance will be normal to the table.

• Yes, there will be an increase in the radiant flux on the table when the plane mirror is placed facing the table above the bulb. This will increase the table’s luminance flux further. So, it results in the increase of the illuminance.

Answer 2

★ Question:-

A bulb is hanging over a table. At which portion of the table is the illuminance maximum? If a plane mirror is placed above the bulb facing the table, will the illuminance on the table increase?

★Answer:-

• The value of the illuminance observed is maximum below the bulb, because light falls normally just below the table.
• The illuminance on the table increase when a plane mirror is placed above the bulb facing the table. This is observed because the radiant flux increases due to the plane mirror.

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