Practice Pakistan questions with answers and explanations.
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Spectacle lenses change the convergence of light entering the eye.
They help focus images correctly on the retina.
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The iris changes the size of the pupil.
This regulates how much light enters the eye.
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The lens focuses incoming light onto the retina.
Photoreceptor cells then convert light into nerve signals.
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Red light has the longest wavelength in the visible spectrum.
Violet has the shortest visible wavelength.
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Violet light has the shortest wavelength among visible colors.
It also has the highest visible-light frequency.
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Wind carries away water vapor near the fabric.
This maintains a concentration difference and speeds evaporation.
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Convection occurs when warmer fluid moves and cooler fluid replaces it.
It happens in liquids and gases.
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Thermal radiation travels as electromagnetic waves.
It does not require a material medium.
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Space between the Sun and Earth is nearly a vacuum.
Solar energy reaches Earth as electromagnetic radiation.
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Wood and many plastics conduct heat poorly.
They reduce heat transfer to the user's hand.
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Metals transfer heat efficiently from the flame to food.
This makes cooking faster and more even.
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Both spoons may have the same temperature.
Metal removes heat from the skin more quickly, creating a colder sensation.
