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Q:

# When one enters a dark room after being in bright light one is not able to see anything clearly for a while because

 A) the retina of the eye moves forward B) the retina of the eye moves backward C) the iris is unable to dilate the pupil immediately to be able to see things D) the eye has no power of accommodation

Answer:   C) the iris is unable to dilate the pupil immediately to be able to see things

Explanation:

The size of the pupil of the automatically adjusts itself according to the intensity of light passing through it; if the intensity is more, the size is less, if less, it is more. So in our case the pupil should dilate i.e , increase in size to be able to see in the dark. This switchover takes some time. But here the entry into the dark room is immediate. So the eye has no time to adjust itself and hence is not able to see at all for a while.

Subject: Physics
Q:

Two metallic plate of equal thickness and coefficient thermal conductivity K1 and K2 put together face to face. A common plate is constructed. What is equivalent K?

 A) K1k2/k1+k2 B) 2k1k2/k1+k2 C) K1+k2/k1k2 D) None

Explanation:

We know that,

The equivalent K =  $\fn_jvn \small \frac{L1+L2}{\frac{L1}{K1}+\frac{L2}{K2}}$

where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.

But here L1 = L2 = L (say)

Then K = L+L/(L/K1 + L/K2)  =  $\fn_jvn \small \frac{2K1K2}{K1+K2}$

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3 81
Q:

"Light years" is the unit of _____?

 A) Acceleration B) Distance C) Light Intensity D) Weight

Explanation:

A Light-year is a distance that light travels in the vacuum in one Julian year (365.25 days).

The light-year is a unit of length used to express astronomical distances. It is about 9.5 trillion kilometers or 5.9 trillion miles.

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5 168
Q:

"The Law of Kepler" is related with which among the following ?

 A) Planetary Motion B) Law of Conservation of energy C) Law of Gravitation D) None

Explanation:

Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.

• Kepler’s three laws of planetary motion can be stated as follows:

(1) All planets move about the Sun in elliptical orbits, having the Sun as one of the foci.

(2) A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time.

(3) The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun.

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10 132
Q:

The Hydraulic Break works on the principle of _____ ?

 A) Pascal's Law B) Boyle's law C) Coulomb's law D) Bernouli's law

Explanation:

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6 297
Q:

What is the full form of "RADAR" ?

 A) Radio Detecting and Ranging B) Region Device and Ranging C) Radio Detect and Rangs D) Radio Device and Ranging