A camera objective has an aperture diameter d . If the aperture is reduced to diameter d 2 , the exposure time under identical conditions of light should be made

For camera, time of exposure ∝ 1 A p e r t u r e 2 ¸ Therefore t 2 t 1 = d 1 d 2 2 t 2 t 1 = d d 2 2 = 4 t 2 t 1 = 4 Therefore exposure time under identical conditions of light should be made 4 fold

Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsOptical instrumentsEasy2 minPYQ_2020

PhysicsEasysingle choice

A camera objective has an aperture diameter $d$ . If the aperture is reduced to diameter $\frac{d}{2}$ , the exposure time under identical conditions of light should be made

Options:

Answer:

Solution:

For camera, time of exposure $\propto \frac{1}{{(A p e r t u r e)}^{2}}$ ¸

Therefore

$\frac{t_{2}}{t_{1}} = {(\frac{d_{1}}{d_{2}})}^{2}$

$\frac{t_{2}}{t_{1}} = {(\frac{d}{\frac{d}{2}})}^{2} = 4$

$\frac{t_{2}}{t_{1}} = 4$

Therefore exposure time under identical conditions of light should be made $4$ fold

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:Geometrical OpticsSubtopic:Optical instruments

⏱ 2mℹ️ Source: PYQ_2020

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